Solution 1 - Check the game is in your My Games list
Check your My Games list and if your game isn't there, please contact Customer Support for further help.
Solution 2 - Check if you received a refund for the game
Refunded purchases will still appear in your My Games list, so if you redownload and try unlocking them, you will see this error as you no longer have a license to unlock the game. If you wish to buy the game again, please contact Customer Support.