BKGaming: Yes... the difference is those systems control the digital software which is what DRM is. This is not the same thing, the digital software is not being controlled or restricted at all here, your access to the server is which you're not entitled to anyway.
1. You are dishonestly pretending that the DRM server is the online play server, just lumping them together as "servers" even though they are two completely different things
The online authentication is an extra (unnecessary) layer that is required not only on their servers, but even if you are hosting your own on a lan.
2. Paying money for a game, does in fact entitle me to it.
3. If I don't want to use their server (or it is gone due to being shut down), I am locked out of online play. For example, lan play where I host my own server on my local network and connect to it via local network. Even though the game code exists and is perfectly able to let me play multiplayer without their DRM server, the lack of DRM server authentication PREVENTS me from doing so because there is special code in the game which exist for the sole purpose of doing that
AstralWanderer: CD-keys are not in themselves DRM if they aren't subject to remote validation (many games only check keys locally against a known blacklist of warez keys) and given that NWN has been quoted as an example, its keys don't qualify as DRM since it is possible (and indeed now necessary) to connect via alternative servers as detailed in the
Discontinued Gamespy support sticky.
keys are DRM.
However the NWN keys are an exception because they are a relic of a DRM system that has been removed from the game with a minimal amount of effort.
The keys originally served to check the authenticity of your game. This has been "disabled" by creating a universal gog key file that works with any system.
For the DLCs the game used to connect to an online server for verification every time you started it or loaded a save file. A CD version of some of the DLC was released (before GOG) which removed that authentication by making a local server emulator that will automatically accept whatever keys were in the key file when the DLC was installed. These DLCs have been packaged with GOG with the same limitation, while DLCs that never had that treatment are simply unavailable (although, some time ago the online verification server went down when EA was hacked and came back a few months later where it now sends a verified signal for any DLC that checks even if you don't own it).
TL:DR - single player used to be DRMed but the DRM was removed in a somewhat sloppy fashion, the end result is that you don't see any DRM as it has been crippled to not go online and just instant approve offline. Or in some cases removed outright
Now, for multiplayer, there was never a master server, what they had was a "master LIST server". A server whose sole job was to list of all available servers. each actual server is ran at home by a home user, no servers were ever ran by bioware. Those servers do not have a username/password authentication, instead they tie your account on that server to your cdkeys. if you steal someone keys you steal their account on all online servers.
instead of redesigning the server software to take a username and password (which would make gog servers incompatible with those who own the steam or CD version), they opted to leave it in.
So in this extremely rare case, CD keys are used not to verify ownership or DRM, but as a username/password combo for user ran servers for legacy and backwards compatibility reasons.
The issue with NWN then isn't that it has DRM, but that it isn't the definitive version of the game. Some DLC is simply not available through GOG. But is available to those who bought it on the bioware online store back in the day before EA stopped selling them.
Although interestingly you can still install the shareware version of those (available for download on bioware forums) and it would work as the full version due to the changes they have made to their online verification servers