Having had this experience recently, it is right that I advise you all of the following before you jump in and buy someone's 'license' without getting the License Number and transfer verified by either vBulletin or XenForo Support!
1. XenForo & vBulletin operate the following Transfer Rule:
Original License Owner: A limit of one transfer per license.
Second Owner: You will NOT be able to transfer/sell this license in the future.
be sure to ask the Seller concerned whether they are the Original Owner, and get them to post a screenshot of vBulletin or XenForo's License number, and then confirmation about the Transfer eligibility from vBulletin or XenForo, before you proceed to pay !
1. XenForo & vBulletin operate the following Transfer Rule:
Original License Owner: A limit of one transfer per license.
Second Owner: You will NOT be able to transfer/sell this license in the future.
be sure to ask the Seller concerned whether they are the Original Owner, and get them to post a screenshot of vBulletin or XenForo's License number, and then confirmation about the Transfer eligibility from vBulletin or XenForo, before you proceed to pay !