An electronic apparatus, having functions on which use limitations can be imposed, in which a variety of functions are loaded on the electronic apparatus by hardware circuitry or by computer programs. Use of a certain function(s) is limited by setting a function limiting flag to "1", provided that an other function(s) are usable within a period of a preset number of days of possible test use. An application is made from the apparatus to a key issuing source for purchasing usable functions. The key issuing source then issues a limitation removing key. The limitation removing key may be acquired from the key issuing source by a mobile phone terminal and transmitted to the apparatus by infrared ray communication. The apparatus rewrites the function limiting flag by this limitation removing key. If the number of days of actual test use has reached the number of days of possible test use, the CPU of the apparatus does not carry out the function(s) the function limiting flag of which is "1".