I am incredibly surprised that this isn't a more pressing concern for Xenforo.
There is a number of info product businesses needing this type of software platform with these types of pricing structures. The fact that this isn't "directly supported" is an oversight in your current business...
Currently I attempting to figure out how to get users access to their purchased product and into a subscription at the same time without have to manually upgrade each user.
It looks similar to this:
--Course Page 1
--Course Page 2