As per title, I have pre-ordered a copy of sins of a solar empire. Very rarely, and by that I mean perhaps once every few months or so, I may want to play a 2 player with a friend and hence, install the game on a second machine I have at home and run a 2 player between them. I used to do this with some old blizzard games such as Starcraft, which had a spawn instalation option for this purpose. I thought it was a good marketing system as my friend end up buying Starcraft and every blizzard game since.

So the question is, since this is probebly going to be one off instalation to second machine, do I need to buy a second copy? Chances are, that after a few games my friend will end up buying himself a copy. Or will there be a starcraft style "spawn" installation option to help with this purpose?