I'm trying to set up account upgrades and I'm a bit confused on how this works. I have a business paypal account and have enabled Instant Payment Notifications as the help page specified. The problem is the part where it states: "You should enter a notification URL of [your Board URL]/payment_callback.php". I've added that for one of my forums, however I currently have 3 xenforo forums and would like account upgrades to be available on each.
How would I set this up through paypal when I only have the option to add one URL? I guess I'm just confused on what that URL actually does.
That URL is used by PayPal to notify forum whenever status of subscription changes. So you'll need to set it up for each forum, which probably (unless there is another way - check paypal documentation or call their support) means creating 3 separate PayPal accounts.