Now that we're live on Steam, and Steam has some Steam-specific online features (not due to favoritism, but because they are the one with an API and server setup of the sort that can provide that), some players may wish to have a Steam copy of the game instead of a copy from whatever platform they previously bought it on.
Never fear! I am assured that you will be able to enter your license keys into the "Activate a product on Steam..." wizard (under My Games in the Steam client), to get a Steam key if you've already bought the game somewhere else. Likewise, the Steam copies of the game include a regular AI War license key (which, despite what the Steam client tells you on first run, you don't have to enter in-game). So if later you want a fully DRM-free copy of AI War, it is available to you even if you buy the Steam version, which is tied to the Steam client like most other Steam games (for reasons of online functionality, in this case, not copy protection).
Here comes the BUT. At the moment, not all of the license keys are going to work for activating your existing copy in Steam. I'm told that all the keys should work within a few days. So you can try entering your license key into the Steam client, and it's possible it might work even right now, but there are perhaps better odds that it will not. I'll post an update here when I have more information about timeframes and so forth on that aspect. I hadn't wanted this part to lag after the initial release, and I don't think Valve did either, but so it goes -- not something I can control.
It appears that all license keys can now be used to activate the Steam version of AI War and allow you to make use of the Steam only features.
Please let us know if this is not the case for you.