An enhancement to a pay station where subscribers can track usage of credit cards or groups of credit cards at parking and other facilities. The subscriber provides a key that can be used with a predetermined hash or encryption algorithm to hash or encrypt every credit card number that enters the system. A database of the coded results for a set of pre-registered credit cards belonging to that subscriber is maintained in the pay station database. Whenever an incoming credit card's coded output matches one of the coded results on the pre-registered list, a log entry can be made in a usage log. The subscriber generally has a list of the coded outputs for each of their pre-registered cards. The subscriber can thus track usage of any of these cards.