I would like to sell my copy of Battlefield 2, but I cant remember if the CD Key was used to create my login account. I would not like to sell the game to someone if they will not be able to create an account and log in with the same CD Key. Does anyone know how this works?
I believe you CAN resell the game (since I've seen it used in stores -- pc) but the buyer has to pay a $20 reactivation fee unless you transfer your entire EA account to them.
Please note that you CANNOT sell Steam games and apparently it is against the EA t&c to transfer your EA account, so you can only sell it if you bought it somewhere other than Steam (probably in box form) and you can find out exactly how to get the reactivation working. I'm fairly certain it exists, but I don't know how to do it, so I would encourage someone who does know to post an answer.
TLDR: It's complicated and you need a lawyer that will cost you way more than the game's worth. If you have a bunch of money to waste you can set a precedent, that's likely worthless as there are more EULAs than there are games.
It's likely the legal fine print will try to make it as difficult as possible for you to do this for any game with an online component if you used it with an online account in any way. I would need to check the Terms of Service for details, unfortunately EA seems to have misplaced it.
It will very likely contain a passage such as this (quoted from another ToS that isn't misplaced from another game from around the same time period, Medal of Honor):
Through this purchase, you are acquiring and EA grants you a personal, limited, non-exclusive license to install and use the Software (...)
The important things to note are the personal and limited restrictions.
Nearly all big titles come with similar language; they're meant to be used by one single person, and publishers included language specific to attempt to prevent 'used game stores' from having a market. Worse, various countries will offer various levels of consumer protection. While a place like Gamestop could put its foot down, a single consumer will have a much harder time if it turns out the online part doesn't work.
Typically, if you've opened it and played it, the EULA forbids resale. Also, when it comes to online accounts, you're typically at the mercy of the server operator and have zero rights. After all, it's their server. That's basically the same in every country. If a game's key is blocked, then that's the end of it.
Used game re-selling is only a thing in so much that most (and almost all older) games themselves do not require registration and online accounts. Whence first sale doctrine may apply. The disk is required to play the game (via DRM) and hence can be viewed as a token of ownership, so since you can no longer play your game without the disk, you can pass it to someone else, or so goes the theory.
But, with online accounts and DRM, it's their rules. And here the law can contradict itself. With the DMCA provision forbidding the circumvention of 'protection measures' in place, a 'protection measure' could be engineered that prevents first sale from ever being applied, by linking the software with a personal account. Thus EA can, if it wants, block accounts that it thinks were resold. Even brick the game remotely (not that I know of cases of publishers doing this, consumers don't like practices like that).
One silver lining: Publishers tend to abandon their older titles eventually. Perhaps one day the servers for the online part will retire, and you can use the abandonware exception of the DMCA (the lynchpin that gives these EULA constructions weight), and ship the game with modifications that allow online play on community servers. That is, if such a community exists. At that point you're really selling the box and not the software license.
So if you don't have any interest in playing the game, why not try it out? Install it on a windows PC, create an account, see if it works. If it does, terminate the account, uninstall it, and you can technically resell it.