A game or other software program is made accessible for execution by clients on a peer-peer network only after a plurality of verifications are made to ensure that control of the software is maintained. With a request sent to a server to access the software, a client includes a nonce and an ID of the user. The server digitally signs a portion of a ticket that is returned to the client, which includes the nonce, a time stamp, and the ID. The ticket is required to access the software. The clients are required to exchange the tickets, verify the digital signature on the portion of each ticket, and use the information therein to confirm that the tickets are current, issued by the correct server, issued to the proper users, and received from the users who are intended to execute the software.