Lyte: vB offers two options: leased and owned. Lease is like renting the software, it expires after a year unless renewed. Those with the owned license have bought their forumware, even if their subscription for yearly updates (for $30/yr) expires, they can still operate the older version. For $120 more, the vB footer can be removed too (but the vB info on the templates have to stay).
It costs alot, but unlike phpBB2, most of the popular forum features come stock (so you don't have to hand code them in yourself). For a busy admin, that saves money in itself.
CKL