OK, I got RealFlight Support called...........the wait time wasn't too bad. Short answer is I can install RealFlight software on as many owned computers as I like. But I can register only one computer at a time for the updates and downloads, etc. If I want to change the registration to a different computer, which is what I am contemplating, that is no sweat as I just log on with a password and initiate the computer change myself.