Hi,
Sorry for the inconvenience caused by the problem, from your description, it seems that Office is not activated, if you have purchased a product, please try the steps in this page to troubleshoot:
Unlicensed Product and activation errors in Office
Also, if your previous subscription or trial plan has expired, you could try the free product
Office for the web(not including Publisher) to edit files.
If we misunderstand your meaning or you met any problem when activating, please tell us the platform you are using, Windows or Mac? We will help you narrow down the issue cause first, and it would be good if you could share a screenshot of the product information
page as well as the error message. (For Mac, please click Word->About Microsoft Word; for Windows, please click File->Account)
Best regards,
Oliver