Why does it say CD Key not verified when you try to go online on FrontLines Fual of war?

The "CD Key not verified" message in Frontlines: Fuel of War typically indicates that the game's CD key has either not been activated or is invalid. This can occur if the key was entered incorrectly during installation or if it has already been used on another account. Additionally, issues with the game's servers or your internet connection may also lead to this error. To resolve the issue, ensure that you have entered the key correctly and check for any server status updates from the game's publisher.