Navionics had a variety of bathymetric charts in the app store that underwent a similar fate when they were bought by Garmin. It didn't matter that I'd paid $20-$30 (forget the exact value) for a lifetime license on a piece of software; they felt the need to shove a crippling update onto the version I'd paid for before releasing a new product line.

On the bright side, in the years since I bought their app a free, better competitor was released, but I still don't think that absolves them of their responsibility.