None of the CD Key/Serial resellers we know about have obtained a proper license. The origin of their CD Keys is unknown, but we do know about numerous occasions when they sell banned / disabled CD Keys so you will not be able to play the game online at all.
Please note that not only is buying CD Keys from these CD Key resellers risky and usually there’s no kind of guarantee, but also Bohemia Interactive is unlikely to get any royalty from these places for the sales. These CD Keys also in no way include a license to the game itself and CD Key resellers are expecting you to pay a considerable amount of money (you can often get similarly priced deals for the full game package) but they also do not provide any type of guarantee.
We can only recommend people buy the game online from respectable sources, like Steam, Sprocket, Direct2Drive, Impulse Driven or Metaboli , or of course a boxed DVD version.
If anyone wishes to ask a question about this information, or is unsure of the validity of a site they're about to purchase from please feel free to PM/Email me: