Program license key issuing method and issuing system

In performing the issuance of a license key to a user through a selling agent or the like on line, the issuance of the license key is performed from a manufacturer to the selling agent or the like in such a manner that information which the selling agent or the like wants to keep in secret is prevented from being transmitted to the manufacturer. Further, when a deadline of a trial period by a trial license key is coming very close, a special license key which extends the deadline of the trial period is issued. In operation, the sales computer receives client information, a product number and a license program name inputted by a purchaser computer and transfers such information from which the client information is eliminated to the license-issuing computer. The license-issuing computer issues the license key when the authentication of the product number is normally finished. Further, the present invention provides a trial license key to a user. When the deadline of the trial period is coming very close so that the extension of the deadline is necessary, a special license key is issued by transmitting the trial license key or the like to the license-issuing computer.