If I remember, when I did try out the add-ons, I was asked to reinsert their disk from time to time. My use of the flight simulator program is strictly eye/thumb coordination. I wasn't interested in all the other aircraft available on the add-ons. I recently purchased a new computer and only loaded the basic RealFlight disk and not the add-ons. I was happy to be able to pass them on to someone who wanted them.

Roger