How do they do this if both computers are not on the internet?
I believe it is only an issue if both computers are on the same LAN.
There is also the practice of Microsoft products "phoning home" (over the Internet) and disabling themselves if MS judges them to be suspicious. It is quite possible that this could be used in conjunction with the a checking for multiple instances of a single license. My apologies for not giving my initial response more consideration. I have been using commercial products (specifically, Adobe PageMaker) that employ this usage restriction enforcement mechanism since before the Web came to prominence.
