These are free upgrade methods:
Windows 7 can be upgraded to 10.
Windows 10 can be upgraded to 11.
Windows 7 cannot be directly upgraded to 11.
Windows 7 can be clean installed to Windows 10.
Windows 10 can be clean installed to Windows 11.
https://www.tenforums.com/tutorials/2267-upgrade-windows-10-a.html
https://www.tenforums.com/tutorials/139745-upgrade-windows-10-windows-7-free.html
https://www.tenforums.com/tutorials/23354-clean-install-windows-10-directly-without-having-upgrade-first.html
https://www.sevenforums.com/tutorials/398027-windows-10-test-try-no-risk-no-install.html
https://www.microsoft.com/en-us/windows/windows-11
https://www.microsoft.com/en-us/windows/windows-11-specifications
https://blogs.windows.com/windows-insider/2021/08/27/update-on-windows-11-minimum-system-requirements-and-the-pc-health-check-app/
https://support.microsoft.com/en-us/windows/ways-to-install-windows-11-e0edbbfb-cfc5-4011-868b-2ce77ac7c70e
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