|1||Log in to your PayPal account|
|2||Click on the Profile subtab|
|3||Click on the Instant Payment Notification Preferences link in the 'Selling Preferences' column|
Check the checkbox to activate Instant Payment Notification and enter the following URL below the checkbox.
If the Instant Payment Notification link is not present you will need to apply for Premier Account or a Business Account from PayPal.
Go to vBulletin Options > vBulletin Options > Paid Subscriptions (link) and enter your PayPal email address in the PayPal email field.