Processes in Microsoft 365 for setting up Office apps, redeeming product keys, and activating licenses.
Hi Helen,
I would need more details to assist you:
How was Office 365 purchased and from where?
Which Office 365 product did you purchase?
Did you register for Office 365 suite using the product key for the first time?
Are you installing Office 365 for the first time?
If not, a Product Key is only needed to set up your Microsoft account for the first time. Once you’ve set up a Microsoft account, you can install or reinstall Office at any time by visiting office.com/myaccount and signing in with your Microsoft account.
Let us know the details and hope the information is helpful.