Using paypal to return to URL with variables

[drooh]

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?

[toplisek]

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:
[cms.paypal.com...]

Source: paypal.com