Does "one device" mean "one device at a time, can revoke and change devices as you change machines" or "one machine, ever, and then re-buy?" I assume the forme

Does "one device" mean "one device at a time, can revoke and change devices as you change machines" or "one machine, ever, and then re-buy?" I assume the former, and I haven't encountered the latter since the 2000s, but just checking.