Now included in every MinorDecliner system is a rich set of customer management features.

You can alert staff of troublemakers by assigning a Banned status to a person and recognize your best customers by making them VIP's 

We also have a Customer Frequency module that alerts you to visits within X hours by the same person. 

This can be used to prevent the case where someone enters your establishment using their legitimate ID, and then passes it back to someone younger who tries to enter with it.