If it is not, the User is notified the first time the subscription date is found to be expired at step P729, and the Subscription ID field 312 is assigned a null value in the Subscriber Database 113 until such time as it is reinstated. [0107] If the subscription is valid, the process returns to the current Subscriber record (FIG. 6) at P723, whose Content ID fields 202 point in turn to the appropr