The Serial Number is your proof of purchase. You can find it based on how you bought the game:
The serial number (or CD key) is required for both installation and initial activation. Test Drive Unlimited 2 (PC, PS3, X360) Test Drive Unlimited 2 Unlock Code And Serial Number
Right-click the game in your Steam Library, select Manage , then click CD Keys . The Serial Number is your proof of purchase
However, I can give you a of what a legitimate TDU2 unlock code or serial number (like from the game manual or a digital purchase) would do: However, I can give you a of what
You may find websites promising a Test Drive Unlimited 2 serial number generator. Be extremely cautious. These files are almost always malware or phishing scams. Because the game is no longer officially sold on most major digital storefronts the safest way to play is to find a physical copy or use community preservation projects that offer the game in a pre-patched state. The Legacy of TDU2