Which are the fields on database to set up a new suscription?

Hello, I am using the Auction Template. I am not working wih Paypal, but ePayco which is a colombian payment gateway. It has not plugin for WordPress. So, what I need is to modify all the fields related to a subscription manually on Php after a confirmation payment in other confirmation file.

Where is the file that generate a key on the database after the subscription? If so. And which are the fields affected?

It is gonna be the same for the products.
I appreciate so much.