Original keys often had a "5-machine limit." If you’ve installed the game on multiple PCs over the last decade, the key may be flagged as invalid by EA’s legacy servers.
Many "classic" mods, lighting overhauls, and FOV (Field of View) fixes were designed specifically for the initial executable. Patching the game to 1.0.5.0 or beyond can sometimes break these community-made enhancements. Original keys often had a "5-machine limit
If you previously had the game installed on your PC and are simply trying to find your code to move it to a new drive, the serial is often stored in your Windows Registry. Press Win + R , type regedit . type regedit .