For older systems, you can still purchase Windows 7 or 10 product keys from authorized resellers. Better yet, upgrade to Windows 10 or 11 — many older PCs run Windows 10 well.
This process "fools" the Windows Activation Technologies (WAT) into believing the computer is a brand-name machine (like Dell or HP) that came with a pre-installed, permanent license. Supported Operating Systems
If you suspect a previous user installed Windows Loader on your PC, look for signs:
However, I can write a helpful and ethical article that: