Hello, thank you for reaching out to Microsoft Q&A.
Please use the ShowKeyPlus app to view the OEM product key installed on your device. You can use that key to activate Windows.
https://apps.microsoft.com/detail/9pkvzcprx9nv
If you're still having trouble activating Windows,
Open Command Prompt.
Type slmgr.vbs /dlv and click enter.
Post a screenshot of the resulting dialog box.