Purchasing base and C&K with Gold
Is it a one-time purchase to have the game or is it for a period of time?
I have done it before but now its saying I need to buy base for 500 coins and then C&K for another 500.
It is a one time purchase. You probably didn't log into the same account or something. You should contact email@example.com with your email, details about when and where you bought the base and C&K games previously with receipt. They will hopefully be able to match up your account(s) and restore your purchase.