Hello, thank you for reaching out to Microsoft Q&A.
You can enroll up to 10 devices with the same Microsoft account in the Windows Extended Security Update (ESU) program.
If you see the message "You've reached the device limit", you can try registering your Microsoft account on the device again, or use a different Microsoft account.
First, go to Settings > Privacy & security and make sure the Find my device feature is turned on. If it is off, turn it ON, then enroll in the ESU program. If you're having issues, reregister your Microsoft account on the same device.
- Go to Settings > Accounts > Your info.
- Switch from a Microsoft account to a local account by selecting Sign in with a local account instead.
- Follow the prompts to complete the setup for the local account.
- Once done, sign out and sign in to your new local account.
- Next, go to Settings > Accounts > Your info > Sign in with a Microsoft account instead.
- Sign in with the Microsoft account that you want to use to register the ESU license.
Then, sign out and sign back in to your profile with that Microsoft account, and try enrolling in the ESU program again.