Customers with expired support licenses shouldn't be allowed to rate

As an author you provide support to a customer for over a year spending hours, days and nights trying to help him or her, then once his/her support license is not valid anymore they ask for help you tell them that they have to renew their support license and that’s where they end up giving you a 1 star rating, is this ethically correct?

@Envato: please disable the option to rate for customers with expired licenses