I had the exact same question years ago and was met with some unenthusiastic responses. I am not judging, I am just informing you from other forums that I have been on. If you do this then you could "potentially" not have a need for the discs anymore and sell them to another party. Just so you know - this method is frowned upon by the X-plane community for this exact reason - I could be wrong, but I believe this is perfectly legal as long as you still possess the original media. I could be wrong, but I believe this is perfectly legal as long as you still possess the original media. That's it! It will never ask for the disk again. Step two: you "mount" that ISO image as a virtual drive in your system. So in other words, I would need to assign 2 separate buttons to achieve reverse thrust on 2 engines.
However, when I look at the XP11 reverse thrust functions, it has them broken down to individual engines. This means you will not be able to use your product key to unlock X-Plane (forcing you to use the time limited demo version) That email address is no longer functional. Step one: you create an ISO copy of your original X-Plane disk. I am trying to assign a joystick button to toggle reverse thrust. X-Plane was not able to store your product key information to preferences, probably because you have no enabled (or functioning) network adapter. Having said that, there are lots of freeware optical drive imaging packages (for example, this one) that can emulate a physical CD/DVD drive. I think it's just asking for the disk every now and then to ensure you are still the owner of the software.