If you are looking for a activation code for a PC installation, you can typically find it on the back of the manual or the inside of the original CD case. Because this is a legacy title from 2004, these codes are generic and tied to the physical media rather than a modern digital account. Commonly used keys for FIFA 2005 include: AS33-9Z98-4Z7R-8S3S-7694 WLL9-2W6P-S685-6S6C-8888 566N-WWA9-U6S8-H6SQ-8888 Quick Game Facts Release Date: October 11, 2004.
This is the number one source for retro FIFA modding. Enthusiasts there have reverse-engineered the CD key algorithm to generate valid keys. While not "official" exclusive keys, they function identically to retail keys. fifa 2005 cd key exclusive
For modern digital re-releases or online purchases, the key is typically sent via the Purchase Receipt Email If you are looking for a activation code