The patent application hints at a world in which AT&T would be offering different, more expensive plans for those wanting to use their data to download movies, or transfer files. Those who do not pay for the right to download movies or transfer files would receive a smaller amount of credit after each use, so that the "non-permissable" activity could not be repeated constantly.
Once a customer is down to zero credits, he could buy additional credits or simply be blocked from the activities that require them. Those who pay for the right to download movies, for example, would never run out of credits.
Before this turns into another debate about net neutrality, let's remember that this is just a patent application and AT&T has not mentioned anything about putting such a plan into action.
via: TorrentFreak, BGR