Hi, Akhilesh. I'm Robinson, and I’m happy to help you today.
Usually, this message is shown when you are using a non-genuine version of Windows.
1-Right-click on Start then click on Windows PowerShell(admin)
2-Type this command and press Enter:
slmgr /dlv
3-Then a pop-up window will open with your license information
If in the "Description" is shown "VOLUME_KMS", this indicates that you are using a non-genuine version of Windows. The "Volume" license is focused on business, governmental or educational institutions.
You will need to contact the seller and check which license type came pre-installed on these computers. If the computers were used by a company and came pre-installed with a "Volume" license you will need to purchase a new Windows license to activate Windows. This license type cannot be transferred.
I hope this information helps. If you have any questions, please let me know and I'll be glad to assist you further.