A method that includes (1) distributing authorization keys from a subscription server to computers on which copies of an application program are to be run, each of the authorization keys being associated with a validity period during which the authorization key will be valid, and (2) at intermittent times that may be as infrequent as the times when the validity periods end, distributing new authorization keys to each of the computers, the keys being distributed electronically in a manner that is transparent to users of the computers.