If you no longer have the manual or box, you can often retrieve the key from your computer's registry: Search Registry and navigate to:

If you own the game on Steam but it asks for a key when you launch it:

If the game refuses to launch or says the key is in use, users on Steam Community suggest "resetting" the local license: Go to the game's installation folder (typically ...\Steam\steamapps\common\Need For Speed Shift 2 Find and run activation.exe "De-authorize this license" activation.exe again and re-enter your CD key when prompted. Steam Community 3. Managing the 5-Machine Activation Limit The game uses TAGES Solidshield DRM

While it might seem like a strange topic for an "interesting essay," the search for a Need for Speed: Shift 2 Unleashed