This short article tells you the problem of upgrade to Windows 10 from Windows 7 and Windows 8.1 especially in some of the Asia countries.
Till now I have 2 Windows 10 Enterprise in production but I need to key in Product Key to activate it.
The Windows may be free if I am able to wait for the 3.85GB to download. Unfortunately they are still huge amount of people out there using 1-2Mbit Internet connect in Asia countries like the one I have at home.
What I did was, I downloaded the Windows 10 from one of my homes using 5 Mbit line. After that I upgraded my Windows 7 and Windows 8.1 using the Windows 10 iso file. That will not be free. You need to have a product key to activate your Windows 10. I really do not think this should be the case.