I am wondering if I can use paypal to return some kind of variable and check that a payment was made.
In my situation, a person on my site subscribes to login and watch videos. When they pay at paypal, I need it to return them to my site and allow them to create a username & password. But I am wondering how it my site will know if there was actually a transaction? Is there some sort of authorization key?
When you use PayPal for online purchases, we never share your financial information with merchants. All you need to give the seller is your email address-because your payment details are already safely stored on our secure servers.
A Verified seller has provided additional evidence of their identity to PayPal by passing key security checks and completing the PayPal Verification process.
API is explained at URL: https://cms.paypal.com/us/cgi-bin/?cmd=_render-content&content_ID=developer/howto_api_overview