According to S. Fischer, R. Dornbush and R. Shmalenzi, the most significant characteristic of money is that it is recognized by all in society as a means of payment. In their opinion, it does not matter what constitutes a commodity used as money, provided that all other people agree to accept it in their calculations  [25]. The same opinion is held by K. R. McConnell and S. L. Brew at Economix, who think money is what they do. Everything that performs the functions of money is money [26].

The question «What is money?» is answered by economist, money theory specialist L. Harris, who functions as a means of circulation, an accounting unit and a means of preservation of value, also revealing the essence of money through their functions [27]. Thus, the necessity to study the functions of electron}] s money is conditioned by the fact that the essence of money is revealed through their functions, and depending on the definition of the functions of money we will have a corresponding idea about them.

Speaking of functions, we use the following definition: function is activity, duty, work; external manifestation of properties of some object in this system of relations. At the same time, as [28] scientists and economists note, the problem of money functions is one of the most debatable. The difference of views on this question concerns not only the interpretation of individual functions, but also their number [29].

Most scholars in the field of money have five functions: a measure of value, a means of circulation, a means of payment, a means of saving, and global money.

E-money, in the process of its functioning perform the function of a measure of value. E-money expresses the value of goods and services through price setting. However, the implementation of this function is not the prerogative of only one or another type (or form) of money. In this case, it is logical to use more abstract notions, i.e. it is more expedient to talk about the social and economic category «money» without dividing them by any attribute.

Therefore, the statement that it is electronic money that serves as a measure of value is incorrect.

It's worth noting that the proposed K. Marx's function of money as a measure of value is met with some criticism. This function is K. Marx’s is represented by a set of two sub-functions: measuring the socially necessary labour inputs contained in a commodity, and establishing the scale of prices. The first sub-function is related to Marx's principled opinion that labor is the only factor in the formation of commodity value 30. This opinion is not shared by modern science, which believes that the cost of goods is determined by a set of factors, one of which is labor.

К. Marx calls both the scale of prices and the measure of values functions of money, but they differ from each other not only for their purpose, but are in very different planes. The measure of value is the social function: the expression of goods in gold hides the reduction of all kinds of work to the general abstract work and the reduction of the latter to the work of gold mining. Price scale is a function of purely technical, expressing the ratio of one amount of gold to another, taken as a unit. It is true that in order for gold to fulfill the function of a measure of value, it must itself be measured, expressed on a certain scale, but this is only a technical condition, a technical prerequisite for the performance of a social function.

There's something else to consider. In particular, K. Marx's theory of money was formulated by him more than 150 years ago. Therefore, some aspects of this theory have lost their relevance in modern conditions.

As for the scale of prices, there is complete agreement, and most researchers consider it to be the first and original function of money. This function of money, according to S. I. Lushin, is, in fact, a prerequisite for the emergence of all other functions of money.

In addition, e-money serves as a measure of value, but also as a sign of exchange value (price sign). However, when e-money is used on the Internet, the intrinsic value of material money disappears, so e-money only serves as a function of the scale of prices [31].

Electronic money as a means of circulation. This function is considered to be the most important function of practical importance. In this function, money provides for the sale and purchase of goods, i.e. the basic economic relationship on which the entire market economy is based. At the same time, Miller P. L. and Van Huz D. D., as well as McConnell K. R. and Brew S. L. put this function on the first place, confirming its superiority in comparison with other functions of money.

It is worth noting that the function of money as a means of circulation is closely related to the function of money as a measure of value: what is expressed in money as a measure of value only as an ideal measure, in their function as a means of circulation is expressed realistically [32]. Indeed, the need for money as a measure of value and the scale of prices arises only when money is used as a means of circulation. On this basis, it can be argued that the means of circulation is a crucial function that reveals the essence of money.

This function can be most clearly transferred to the sphere of electronic money. With a certain value, e-money can mediate the movement of goods and services, both online and offline, with sufficient infrastructure development. Taking into account the process of evolution of money, characterized by the transition from goods and money of real value to money of inferior value, the replacement of real money with money of inferior value follows the essence of the process of commodity-money circulation, in which money only fleetingly mediates the process of buying and selling goods, electronic money becomes a natural means of circulation. Thus, the use of electronic money, which does not only have a real value, but also a material basis, as a means of circulation seems to be the most appropriate.

Circulation of inferior money is associated with only one problem, whether or not the seller of the goods recognizes or does not recognize it, whether it is of general importance.

One of the functions of modern money is the function of a means of payment. This function is proof of the development and complication of money as an economic category.

Historically, the function of a means of payment has been developed by separating the moment of transfer of goods from the moment of payment for blacks. The immediate exchange of equivalents was replaced by an exchange within a certain period of time. The true development of this function occurred when the movement of money from one owner  to another was no longer dependent on the movement of the commodity equivalent. Money began to act as an independent representative of value. However, the above mentioned refers to the money having a real, coinciding with the nominal (nominal) value. Money must be of value not only in the possibility of exchange for other material goods (for in this case there will be identification with the means of exchange), but also of value as such (e.g., treasures). In the conditions of circulation of gold money, this condition is fully met, but in today's world, where money is credit and, in fact, nothing is secured, this function may face certain difficulties. Thus, the function of money as a means of payment is secondary to the means  of circulation.

Taking into account the effect of the law on saving public labour, which requires saving of money turnover costs, it was noted above that the inferiority of money does not prevent them from being a full-fledged means of circulation [33]. As far as electronic money is concerned as a means of payment is concerned, this fact somewhat limits the possibility of using it as such: payment of taxes and other obligatory payments, repayment of debt, etc. In other words, this function in the sphere of electronic money will be fully realized if electronic money has a full internal value, which is impossible because it is intangible matter. In addition, electronic money will be able to function as a means of payment, provided that it is not possible not to accept these funds. Consequently, electronic money should be either a highly secure means of payment that is secured by the property and authority of its issuer, or the obligation to accept it as a payment should be enshrined in law.

Saving money.  According to K. P. McConnell and C. J. T.'s point of view. Brew, the money, being the most liquid of all assets, is very convenient to store wealth.

However, it is more expedient to speak not about the function of a means of saving, but about the means of preservation of value. This function arose as a result of the development of the means of payment function. Depositing money is using it as a means of payment, and staying on deposit and waiting for interest is a means of saving and saving. According to S. I. Lushin, this function is especially characteristic of modern times, as money has become symbolic. Gold money is valuable in its own right and does not need an additional function to preserve value. The value retention function is not just a development of the value retention function as a means of payment, but is very often a condition of the latter.

Moreover, if money is accepted as a means of exchange, it should also be a means of preserving value. Otherwise [34], if the money cannot be used to make purchases in the future, then today they will not be accepted in exchange for goods «services,» that is, will not be recognized as a means of exchange.

Electronic money has a somewhat limited accumulation and saving function. Firstly, a simple qualitative analysis shows that e-money is associated with much greater risks than traditional money issued by central and commercial banks. Second, the use of electronic money does not currently guarantee its holder a certain income from its storage or any other benefits from its use, similar to bank deposits.

However, e-money does serve as a means of preserving value, due to the possible interval between the arrival of e-money to its owner (regardless of the way in which it is received) and the moment in which it is used as a medium of exchange.

E-money will also be considered as a means of preserving value at any point in time when it is used as a means of payment.

The world's money. Money in the process of its functioning can also perform the function of world money, i.e. it can be used for money transactions between countries. In the current environment, national money cannot perform this function, except for reserve currencies.

However, e-money that does not operate within the territorial boundaries of any country (in this case, e-money that functions on the Internet and is called network money by some scientists) is capable of disclosing its essence as global money. However, in our opinion, it is more appropriate to call this function as a means of cross-border settlement.

In this case, electronic money contributes to the gradual internationalization of money circulation, ensuring the smooth conduct of international transactions, expanding the boundaries of the payment space through the development of telecommunications technologies.

At the same time, e-money with greater efficiency will perform the function of cross-border settlements within the framework of certain integration entities (Eurozone, Customs Union of Russia, Belarus, Kazakhstan), taking into account the unified legislation, as well as unified supervisory requirements to the relevant activities and a single level of technological development of the payment infrastructure. In particular, in Europe, a single payment space in euros (SEPA) is used for this purpose. SEPA will allow users to make non-cash payments in euros to any recipient located anywhere in the euro area, using a single bank account and a single set of payment instruments. As a result, all retail payments in euros become domestic, as there is no distinction between national and cross-border payments in the euro zone.35 In order to implement this function of electronic money, it is necessary to create and legislate an analogue of the European SEPA system, i.e. legal and technological infrastructure, as well as to unify the standards and principles of transactions.

Thus, it can be argued that e-money performs all the classical functions of traditional credit money, although some functions or elements of it are somewhat modified.

The function of electronic money as a means of circulation is dominant. However, at the moment there are no legal or methodological obstacles to the implementation of other functions of electronic money, which is inherent in traditional money. The problem of implementing these functions comes down to solving organizational issues, as well as, possibly, to the emergence of major players in this area, who have impressive authority and trust, both from the state and the general public.