Here's what got me - if you stop your subscription you will never be able to open your files without paying the minimum monthly charge to make the app available to you.

I don't know if my own reasoning makes sense in terms of how the technology changes. I was asked a few weeks ago if I could supply some PDF spreads of a book project from 2000. It was created in Quark . I can't open it, Quark was made for Classic OS, the files are dead to me. And I can see this happening with my body of work produced in ID. Everything is saved to PDF now for proofing and review, but if source files are unavailable I'm stuck. At least now I'll have a DVD install of CS6 but who knows if that'll run in 5 years or so. Seems optical drives are dinosaurs, yet my entire design career is archived on DVDs.