WARNING: Downloads for Office for Mac 2011 will no longer be available for Office 365 after September 22, 2016 from the Office 365 portals. If you have a one-time purchase of Office for Mac 2011, you will still be able to install your Office using your product key.
If you move Office to another computer, or make significant changes to your computer, you might see this message:
"Online activation did not complete successfully because the product key has been used the maximum number of times permitted."
Office 365 subscription
Office as a one-time purchase
If you move Office to another computer or make significant changes to your computer, like reformatting it, you’ll need to activate by phone.
In the activation wizard, click Activate By Phone, and follow the instructions.