Processes in Microsoft 365 for setting up Office apps, redeeming product keys, and activating licenses.
For Office Home & Student 2016, the license is normally tied to the Microsoft account that was used to redeem or activate it. Re-creating a Microsoft account with the same email address does not restore the original Office license association if the original account is no longer available.
The most useful checks are:
- In an Office app, open File > Account and check Product Information > Belongs to. That shows the account currently associated with the installed Office copy.
- Sign in to Services & subscriptions with every possible personal Microsoft account the customer may have used. If the Office product is not listed there, that account is not the one associated with the license.
- If Office shows activation errors, make sure there is only one Office installation present. In Control Panel > Programs > Programs and Features, search for office and uninstall any duplicate or unused Office versions, then restart the PC.
- If the customer cannot access the original Microsoft account, use the Microsoft account recovery options. Microsoft also provides a sign-in helper tool for cases where the account email or password is no longer working.
Given the specific symptom — Office reports that the product key was already activated on 18 May 2018 with a different account, while the current account does not show the license — the practical next step is to contact Microsoft Support and provide proof of purchase and the original product key. That is also the documented path when someone else installed Office and the wrong account became associated with the product.
If support confirms the original account cannot be recovered, the context does not provide a self-service way to transfer that Office license to a newly created Microsoft account.
- Why do I need an account to sign in to Microsoft 365 or Office? | Microsoft Support
- Unlicensed Product and activation errors in Office | Microsoft Support
- About accounts in Office | Microsoft Support
- Check products or services where you used your Microsoft account | Microsoft Support
- Problems renewing a Microsoft 365 subscription | Microsoft Support
- Get help with your Microsoft account