Hello PrakashPeedikayil,
Good day!
I'm Jericho, a fellow customer and an individual advisor. I am happy to assist you!
For your case, if you have your Microsoft account synced with your Windows system then you may just go to Settings > Update & security > Activation.
If you only have a local account, you need to add a Microsoft Account to Windows 10. Go to Settings > Update & security > Activation, click Add an account and complete the process.
If you are having issues activating your account, you may try follow the steps below.
Go to Settings > Update & security > Activation, select Troubleshoot, sign-in with your Microsoft Account. Choose the computer in the list of digital licenses associated with your account, select 'This is the device I’m using right now' and click Activate.
For all other steps, please refer to this link below.
https://support.microsoft.com/en-ph/help/12440/...
Hope that helps! Please let me know if you have other queries/concerns.
Cheers,
Jericho