I'm looking for an add-on which can help me incorporate "Premium membership" on our forum, where paying users will have a number of benefits over regular users. Basically, the add-on should give users the possibility to "purchase a premium membership" for a specific time (ex. weekly, monthly, yearly subscription) by paying via PayPal or other payment gateways, and Forum Administrators should have the possibility to approve or disapprove memberships. When approved, premium members should get transferred to the Premium members group (with the proper privileges) and when the subscription ends - they should be transferred to Regular users group.
Anyone familiar with an add-on that meets any of these requirements?