Yes did that yesterday. Used Rufus to add the matching ISO to a USB stick, to be used for updating and a clean install. In Windows 7 navigated to the USB stick and ran Setup. Updated Windows 7 Home Premium OEM to Windows 10 Home and it immediately showed activated as well. No downloads except the latest patches released since the ISO was made available. Will do a clean install some time in the future. Also noticed Windows.old is about 11GB.