Activation helps verify that your copy of Windows is genuine and hasn’t been used on more devices than the Microsoft Software License Terms allow.
If you're unable to activate Windows 10, the Activation troubleshooter could help. To use the troubleshooter, select the Start button, then select Settings > Update & Security > Activation , and then select Troubleshoot.
Open Troubleshoot settings
You must be signed in as an administrator to use this option. If you're not already an administrator, for more info, see Create a local user or administrator account in Windows 10. The Troubleshoot option is available only if your copy of Windows 10 (Version 1607 or later) isn't activated. Once you activate, the option disappears.
Windows activation requires internet connection. For more info, see Get online.
The following are some problems that the troubleshooter might fix: