If you have a licensed Windows 10 Pro machine, Microsoft treats this as a version update, not a new purchase. Windows 11 requirements - Microsoft Learn
Specific groups, such as students at participating institutions, can often access Windows 11 Pro/Education for free through programs like Azure Dev Tools for Teaching. Eligibility and System Requirements windows 11 pro upgrade free
Use the PC Health Check app to verify compatibility instantly. If you have a licensed Windows 10 Pro