More specifically - a data breech (hackers) got into Bioware several years ago, which prompted the closure of the old bioware forums, where the cd keys were stored.
Bioware did not explicitly say the keys were gone, but one can assume that after all this time - they have no plans of making those keys easily available to us.
It might be possible to request bioware support to give you a new cdkey if you can prove purchase.
Receipt, Box, Instruction manual etc
I wouldnt hold thy breath...
Not that I would condone piracy - it should be noted that with the official master server gone, the only purpose the cdkeys have now, is to prevent multiple people using the same key on the same server.
Eg:
ABC-DEF-ABC - cannot be used on Server A
If someone else is using
ABC-DEF-ABC
In fact - GOG ship the game to you with two CDKeys - the default that everyone has access to, and then you e-mail them for your own personal multiplayer one.
In any case - there has been some debate on the ethics of being forced to purchase the game twice due to a mishap on bioware's end.
It becomes somewhat circular in that some people say that Bioware provided a service which led to us trusting them with our cdkeys, the other people say that the cdkeys are your own property and you need to guard them yourself -
Both arguments are true - and yet somewhat moot given that bioware are unlikely to try and resolve any lost cdkey issues.
Im somewhat lucky I guess because I have always just copy and pasted my install directory from machine to machine.