The key which I purchased didn't work and they are trying to not refund me. I purchased the key immediately from another seller and it worked without any issue. They just keep telling me to remove win 10 and make fresh installation which is not needed. I have 200 programs installed, so how can I remove and install them again? When you upgrade windows, you don't need to uninstall or fresh installation. Just insert a new key and the system will be upgraded if the key is not fake. Anyway, I purchased from another seller and upgraded to win 10 pro without any installation.