Abstract: In order to prevent software sold by a software sale server to a user and downloaded to a computer of the user from being copied and used illegally, the software server is informed of apparatus information unique to the computer and a user ID assigned to the user when the computer of the user is sold to the user. When the user purchases software from the software server, the software server saves the name and version of the software, associating the name and the version with the user ID and the apparatus information. When the user activates the software for the first time, the computer transmits the user ID, the apparatus information, the software name and the software version to the software server to be collated with their respective counterparts, which were saved before. If a result of collation indicates that the pieces of information match their counterparts, a license key for activating the software is transmitted to the computer of the user.