I know that stock vBulletin comes with a basic subscription manager but it lacks in some important features. This is where I think DBT could come in.
- Notifications of subscriptions ending through PM, visitor message, DBT notifications, or all of the above.
- Separate notification for each subscription as some sites have multiple.
- Subscription gifting - one member purchases subscription for another. The member receiving the gift subscription gets notification of the gift.
- Subscription page for description of subscription.
More as they come to me.