Well, start multiple accounts and buy multiple copies of the game? :-P
Seriously, you've got a GOG.com games? You surely can install/copy it on how much systems you like....

Of course he can. That doesn't mean that he should.

I agree. Let each person participating in the lan make an account. Or maybe contact support.

If, for business accounting reasons, all the licenses need to purchased in a single transaction through one account, I'm certain GOG Support will be thrilled to help work that out.

Your boss is paying for gaming? Where do you work and can I get a job there?

Each person should create an account.
Another option is is to create a work account with user 1, user 2 etc.
e.g. My_Business - User 1, My_ Business - User 2, My_Business - User 3, etc.
This would allow the company own the titles and let different employees to play the game.
It is a thought anyway, but I will say I too wondered why users are locked out of buying more than one copy of a game.

I am willing to bet (though I could be wrong) that the team never thought of the idea of multiple copy purchases, since there is no DRM on the games you can install on as many computers as you want - most people tend to buy for personal purchases, not for group purchases.
I think the team here will work something out with the OP, and probably put that feature in (even if its little used) for the future [hint hint ;)]

hmm. this attitude annoys me. when you play monopoly, does everyone bring their own copy of the game? of course not. multiple people play using one copy of the game. i don't see why it should be any different with software.
and just for a quick memory jog -- starcraft allowed owners to "spawn" a copy of the game on another computer for the purpose of multiplayer LAN games. nowadays, most games don't even support LAN play, and we're expected to buy multiple copies of the game to play with friends.
i also think that GOG is quite clear that they aren't selling licenses -- their no DRM model demonstrates that they are selling a product that the buyer actually owns.

I see your points but i would agree that multiple purchases would be the right thing to do. Technically speaking i could give my copies of gog games to my friends family whoever and only pay the once but then thats just spitting in the face of gogs no drm trust. Granted i know you are speaking about LAN games so its a little different to just copying a bunch of games over and over again for free distribution but i feel my point still stands. If gog have respected us enough to do what they have i feel we should all repay them their trust with the kind of support shown by buying multiple copies of the game for LAN parties when you technically dont have to.
thats the way i see it anyway

I feel it's a personal choice. If you were having a LAN party at your house, would you expect everyone to buy a copy of the game? I wouldn't. But I wouldn't let them take a copy home with them either.
I think if the business buys one copy, it would be fine, as long as the people from that business weren't taking copies home with them. If they want to do that, then yes, they should buy a copy each.

I think it boils down to just send Support an email and ask what they prefer. And let us know what they say ;)

The problem with that is that it becomes hard to admin as more copies are required, and probably requires multiple email addresses set up et al.
When playing Monopoly, there is only ever one copy of the game in existence within the play group - thats not what happens with computer games.
And you are buying a license, the fact that it doesn't have DRM doesn't change that - when dealing with copyright, you only ever buy a license.
Unless the game specifically allows this in its license, then for a business buying multiple copies is the only safe thing to do.
Also, the very fact that Gog.com are selling DRM free games is the reason I want to do this properly and reward them with money - sure, I could just use it on multiple machines because theres no DRM to stop me, but I like the way Gog.com works and thus want to remain honest.

richardprice, that's really the difference between the two mediums, though. computers only work because they make copies of information -- even when playing on a single computer, the information is copied multiple times on the same computer (between the hard drive and RAM). but we also have to keep in mind user expectations. any review of the history of copyright will show that courts do take into consideration how people expect to be able to interact with their culture, and software shouldn't be any exception.
software is just as much a piece of culture as a book. and yet, when i purchase a book, which is a copyrighted material, i am not purchasing a license, i am purchasing a product. i have certain rights with that product -- i have the right to share it, lend it, sell it, read it on a train, in my room, carry it wherever i want, etc. there are expectations of what i can do with a book, just as there are expectations about what people can do with games. for a long time, we've expected to be able to play any kind of game, whether physical or virtual, with multiple people using only one copy of the game. i don't think that software should be any different in this regard. i don't think that it is unreasonable to assume, as we have been for many years, that a game with multiplayer can be played by multiple people at once.
but the software industry does think itself special. courts have said that simply calling software a license doesn't make it one. there is a single transaction and a physical good passes hands. that's enough for US courts to deem software a product, not a license. and the legality of EULAs are questionable -- some lower court cases have held them legally binding, others have not. so instead of finding a legal pathway, software companies are coming up with technological quick-fixes to things they don't like, such as dropping LAN support making it near impossible to play a multiplayer game with a multiple people with a single copy. gamers swallowed that without a fight. one expectation that they have been successful in changing, it seems, is the expectation that multiple people can play a multiplayer game with a single copy.
EDIT (added response to bladderofdoom):
bladderofdoom, there is a big difference between wide, free distribution and sharing amongst friends/family. if we apply your example to music, then the cassette recorder would have been outlawed. in fact, this was tried by the music industry, but the courts shot that attempt down. people made cassette tape copies (then later CD-R copies, and then raw mp3 file copies) of albums to give to their friends and family, an expected practice which the courts agreed did not violate copyright law. sharing a copy of a game amongst friends in order to use that game's multiplayer function isn't any different in my opinion.

Just wait until Board Game Companies figure out that they only have to put in one set of playing pieces per game and anyone that wants to play must buy their own copy of the same board game! :oP