Processing for extending function of an information processing apparatus having functions, the use of which is restricted, is managed by canceling the restriction of the use of function in association with an information storing device which is connected to information processing apparatus A, B. The information storing device holds information on a list of product keys and the number of possible function extensions (the number of restriction cancellations and the number of licenses) as information for canceling the restriction in advance. The number of information processing apparatus, the functions of which are extended, is managed by reducing the number of possible function extensions each time when one function of the information processing apparatus A is extended. Unnecessary function is deleted from the information processing apparatus A so as to increase the number of licenses. Correspondingly, the function of the information processing apparatus B can be extended.