I recently bought Windows 10 Pro license from Amazon for $10 (normal price is $80). It had over 600 ratings, tens of positive reviews along the line "if it does

I recently bought Windows 10 Pro license from Amazon for $10 (normal price is $80). It had over 600 ratings, tens of positive reviews along the line "if it doesn't work immediately, phone Microsoft and they will fix it for you". It worked immediately for me. Apparently they are Windows licenses recovered from broken laptops and such, but anyway.