A license issuing means issues a license file to an application program using a library containing a plurality of functions. The license file contains licensed function information for specifying a function allowed to be used among the plurality of functions contained in the library. An authentication means performs license authentication based on the license file. A function activation means activates a function specified by the licensed function information among the plurality of functions in the library based on a result of the license authentication. A program execution means executes the application program by using the activated function.