Finally, money serves as a standard of deferred payment or a unit of account over time. When you borrow, the amount to be repaid next year is measured in pounds sterling. Although convenient, this is not and essential function of money. UK citizens can get bank loans specifying in dollars the amount that must be repaid next year. Thus the key feature of money is its use as a medium of exchange, convenient to make money the unit of account and standard of deferred payment as well.