Hello, first it's a pleasure to be able to help you today.
My name is Georges C. welcome to the community.
Hello EsmaSE, If it's an Office 365 key, you don't need the key just go to the Microsoft account where that license is linked.
https://answers.microsoft.com/pt-br/msoffice/fo...
If it is the Windows license and it is working you can use this software to read the activation key:
ProduKey - Recover lost product key (CD-Key) of Windows/MS-Office/SQL Server (nirsoft.net)
https://www.nirsoft.net/utils/product_cd_key_vi...
Note (Standard Disclaimer): This is a third party link that is not Microsoft's property, so you might encounter advertising on the website.
This software also shows the keys to lifetime versions of Office.
If it is the Windows license and it has come pre installed on the computer it must have a label with the activation key, or alternatively the license may be in the BIOS and to read open a CMD window and type the following command followed by enter:wmic path SoftwareLicensingService get OA3xOriginalProductKey
If you can't, the best way to get help for your case would be to contact Office support.
Contact Microsoft Office Support
https://support.microsoft.com/en-us/topic/conta...