Developing an app that people pay a monthly subscription to use. They can pay monthly or a year in advance for a reduced price.
What is the best way to make sure they are up to date?
My best guess is, when they make a payment, an expiration date is calculated and then each time they log in the app checks to see if the current date is < the expiration date.
What's the best way to do this? What are the pitfalls? What are necessary maintenance requirements?