PHP: Let user download purchased file ONLY

Question

I am forseeing a problem with allowing customers who purchase some content from me via PayPal. I will offer multiple, intangible goods. When someone completes their purchase for

Answer 1

One of the simplest things you could implement is a logging system to track the user's purchases. You can cross reference the requested ID with IDs stored related to the user's purchases. If they are not related, don't serve the file.