Hi, jcdenton, and thanks for your interest! While technically it's against the license agreement to do this, the game lacks DRM to police you in this manner. Chris Park (x4000, the Arcen Games head) has written about this topic before in a few posts, located
here and
here, if you care to read them for a more in-depth response that's straight from the horse's mouth. The basic jist, though, is that we ask users not to use multiple copies of their game simultaneously, which rules out multiplayer play using a single key. However, as said before, we're not going to police you and we trust you to "do the right thing", as Chris put it.
If you're okay with using the current beta versions (which are likely to be in pretty solid shape, but may have bugs here or there; I'm not aware of anything particularly major in the current beta),
prerelease 2.001ZE is out, which features a longer trial time than the current official version (2.0) that is available on our and our distribution partners' web sites. Trial time there is 3 hours per game, as opposed to the 1 hour limit per game in version 2.0, which should be plenty to figure out if this game clicks for someone. Furthermore, I recommend that everyone starting AI War take a look at the tutorials to try to figure out the game. The intermediate tutorial (a miniature campaign with some useful hints for helping the player through) has no time limit in the trial version of the game, so that could be a good way of helping her learn the game and gauging if she'd like it.
Finally, if you'd like to take the chance on a full version (though, frankly, I think the 3 hour trial should be enough to see if it's right for her), AI War is also available at a 50% discount on Steam right now for just $9.99, so the barrier to entry is especially low at the moment.
I'm sure Chris will chime in later today with more thoughts of his own, especially since he's also a co-op gamer who enjoys playing games with his wife, but I hope this is helpful for now.
Thanks for posting, and I hope this was helpful!