Active passive licesening when patching

Hi

I have a customer who is running SQL Server 2012 Standard Edition without Software Assurance. Because of the fact that the customer hasn't got Software Assurance on his server, he is bound to the 90-day reassign rule (from active to passive). If Microsoft releases updates or patches every week, how is the customer supposed to install patches/updates every week if he can't reassign the licenses within 90 days?

Thanks!