Since EA transitioned from Origin to the EA App, some legacy keys don't migrate automatically. If your valid key isn't working, you may need to contact EA Support with proof of purchase to have the game manually added to your modern library.
: Authorized resellers, such as online marketplaces or game stores, often carry copies of NFS Shift 2 Unleashed with valid serial numbers. When purchasing from resellers, make sure they are authorized by the game's publisher to avoid counterfeit products. nfs shift 2 unleashed serial number pc
Activating a serial number for Need for Speed: Shift 2 Unleashed Since EA transitioned from Origin to the EA