1. Go to Settings > System > Activation > Update product key > Change product key.

2. Enter the 25-character code in the pop-up window. Alternatively, enter the key during the installation process.

3. Now click on 'Next' to redeem it.

4. Your new operating system is now activated. Enjoy!

5. For other activation methods go here: https://support.microsoft.com/en-us/windows/activate-windows-c39005d4-95ee-b91e-b399-2820fda32227#WindowsVersion=Windows_11