Again, the EULA states that you can install it on ONE other personal computer that you own and are the primary user of (like your notebook). However, you cannot use both computers at once (so, you can have your friend come over and play single-player on your notebook but you can't play with him at the same time on your Desktop). So you couldn't install it on all three of your computers, anyway (legally, nothing stops you from doing it other than yourself since it is DRM-free).
Since, it appears, LAN games "phone home" to Stardock you are going to be required to have a copy per player in order to play together (not the case for Single-Player which you could freely distribute illegally and everyone could play). Again, I think its dishonest to say you support LAN play when it phones home. And they'll need more than their own account on Impulse, they will need their own SERIAL number, which means they have to buy the game. I believe that Stardock will be aggressively updating this game for balance, which is why they are hosting the data on their own servers, so that is the justification for it, even if I disagree.