It's possible to upgrade your Windows license without reinstalling, but you may need to ensure Windows recognizes your new M365 E5 subscription properly.
- Open Settings on your PC.
- Go to "Update & Security" and then "Activation."
- Click on the "Troubleshoot" button under "Activate Windows."
- Sign in with your Microsoft account associated with your M365 E5 subscription. ================
- Sign in to the Microsoft 365 admin center (https://www.microsoft.com/en-us/microsoft-365/business/microsoft-365-administration).
- Go to "Devices" and then "Devices."
- Locate your specific PC and ensure the license assigned is indeed M365 E5.