When you try to create a new user account in Ensemble Studios Online (ESO) to play multiplayer games in Microsoft Age of Empires III, you receive the following error message:
Account creation failed:  This CDKey cannot be used to create any further accounts.
This issue occurs if you have reached the maximum number of accounts that may be created for the product key that you currently use.
To resolve this issue, use one of the following methods.
Method 1: Use the original user account
You can play a multiplayer session in Age of Empires III by using the original user account that you created in ESO. If you have forgotten your account name or password, you can retrieve the account name or password. For more information about how to use ESO to reset forgotten account names and passwords that you created to play multiplayer games, click the following article number to view the article in the Microsoft Knowledge Base:
911712 Age of Empires III: How to use Ensemble Studios Online to reset forgotten account names and passwords
Method 2: Purchase additional copies of Age of Empires III
Purchase additional copies of Age of Empires III to play the game in ESO by using multiple accounts and computers. You can install each copy of Age of Empires III by using the unique unregistered product key that is provided with each retail purchase of Age of Empires III. To purchase additional copies of Age of Empires III, visit the following Microsoft Web site: