i always thought the roms were the license.
you run winuae, you can use the rom "images" from your amiga. therefore the acutal rom code is only in use by one machine at a time.
same as mac emulation prior to OS9.1. its perfectly legal provided the machine that the rom images came from is not running at the same time that the emulator running with those rom images is running too.
basicly, one set of roms, one running machine.
on a side note, in my opinion, hyperion deserve to win the lottery and more for all they've done, and not just for OS4. but for the game ports, and all the crap from that money laundering operation known as amiga.inc.