If you are seeing a notification that your version of WIndows 11 has reached end of support, that usually just indicates your version of WIndows 11 is very old and just needs to be updated, you should not need to purchase a new Windows licence or re-install Windows.
1
Click your Start Button, type winver and hit Enter
Please provide a screenshot of the resulting dialog.
2
Click your Start Button, then just type msinfo and press Enter, please provide a screenshot of the resulting System Information window.