It is only available on that receiver, however, if you order the same event for the same period from multiple receivers, you are only charged once. For instance when I have people over for UFC in the Summers we rent on both the 622 and 722k so that it is showing in HD on the deck and in the house.
If you order online it is supposed to be active for all receivers without having to do anything else from the receivers, but I have never tried this, so I'm not positive that is how it works in reality.