A family of Microsoft spreadsheet software with tools for analyzing, charting, and communicating data.
Hello Arthur Lim
Booting the iMac from the external SSD may have caused Office to lose its previous activation information.
Please first sign in to Microsoft Services & subscriptions using the Microsoft account originally used to redeem or purchase Office 2016. Check whether Office 2016 for Mac appears there.
Then open Word or Excel and select Sign in or Activate, and use that same Microsoft account. If the product was originally supplied with a key, do not post the key here. A key that has already been redeemed normally cannot be used again; activation must be completed through the Microsoft account linked to it.
If activation still fails, please let us know:
- The exact Office 2016 edition, such as Home & Student or Home & Business
- The macOS version installed on the external SSD
- The complete activation error message
- Whether Office 2016 appears under Services & subscriptions
Please note that Office 2016 reached the end of support on October 14, 2025. We recommend upgrading to a currently supported version of Office to continue receiving security updates and technical support.
A valid perpetual license does not automatically become invalid, but compatibility and activation support may be limited on newer macOS versions.
Please feel free reply back to this post if you need further assistance, I'll be happy to help.