Personally, I have always severely detested this "subscription" model for computer-based software. I understand it, but I hate it. Always have. I don't force that model on others who my own software, btw.
I have several old paper charts that I take out for training, simulation, or just looking something up purposes. I should be able to do the same thing with my software data that I paid for. I had to buy the paper charts. I had to buy the data. They are now mine. It is not legal, but more importantly it is not safe to fly with outdated charts, the primary purpose of the iFly products, and I don't and I don't advise anyone else to do so either.
In all these years I've been paying for iFly, I've used it in the air a whole TWO times, but I still continue buying it because I am subject to flying with it at any time.
That's my two cents, that absolutely no one asked for.