title: How to secure paypal integration for website
body: <p>I have been using paypal in the past for selling stuff through my website ( e.g. memberships ) but I always had to verify through paypal whether the user really bought the membership (for example) before I could assign it to his/her account. Now I was wondering if there's a way that I can put a paypal purchase button onto my webpage to ( for example ) purchase a membership and then once the user paid, he'll automaticly be assigned the membership on my website ( e.g. there's a page purchase_result.php which assigns the membership, but ONLY if the user really bought it through paypal ). How can I make sure the user actually bought the item through paypal on the return page on my website?</p>
  
  <p>Thanks in advance,
  Skyfe.</p>
  
  <p>btw, I hope my question can be understood</p>