To protect additional computers (up to 10) with your Premium subscription follow the 'Activating additional computers with your Premium account' section above. Re-protect your computers via that dashboard (See How to reinstall Sophos Home ) L og in to your existing Premium activated account There are 2 options to fix this, please follow the one that applies best to your case: Since the key is in use by another account, you may need to re-protect the current computer using that other (Premium) account. License keys can be activated one time only, and will be linked to the email address used to access the Sophos Home Dashboard when the activation took place. This happens when trying to use a key that has already been activated. Why did I receive a message stating The key is already used appears when I try to activate Premium ?