I wish that more renderers would offer PLE editions, for those that don't render for living and can't afford to spend money on tools that will never pay off. Something like Brzil Rio was, or Corona A6 is. By the way, i think, Corona even allows commercial use with A6!
Anyway, i don't think that it's counting as commercial use if you have Vray demo installed on your pc just for that Max could be able to read Vray materials. I could be wrong, though.