Hi Sodalin Sen,
Thank you for writing to Microsoft Community Forums.
Ideally, if you are activating a copy of Windows, depending on how you got your copy of Windows 10, you'll need either a 25-character product key or a digital license to activate it. A digital license (called a digital entitlement in Windows 10, Version 1511) is a method of activation in Windows 10 that doesn't require you to enter a product key. Without one of these, you won't be able to activate your device.
To check if your copy of Windows is Retail or Volume License, you can:
- Open Command Prompt
- Type slmgr /dlv
- This will open Windows Script Host window.
- The “Product Key Channel” line item will show you if it is Retail or VLK(Volume License)
Usually, if you are not using a genuine Microsoft product key, you may start receiving notifications on your PC that the Microsoft software you're running may not be genuine or activated.
To know more about Genuine Microsoft product, please refer our How to Tell webpage.
For more on activation, please refer Activate Windows 10
Regards,
Prakhar Khare
Microsoft Community – Moderator