How do I set up DB to control subscription access?

I'm trying to plan how to authorize users to access a page, based on the currency of their subscription payments. They might pay a typical one month in advance subscription each month, or they might pay six months or a year in advance (possibly with a discount). 

I'm thinking I would control access through, for instance, "ExpireDate > today()". And I would calculate ExpireDate, based on payments. This is completely new to me, and web searches get me into software companies' software subscriptions—no how-tos.

How would you handle this? I will create another table to record the user's payments. 

If you know of an online resource that discusses this topic, please share!

Thanks!

John