Like everything, apps and engines have a natural lifespan. If the developer has the strength of will to continue to develop/maintain an app, then one of the following happens:
- Everything stays the same and the app just gets better (e.g. Mixtikl 2 > Mixtikl 5);
- The app keeps the same name but becomes a new app (e.g. Noatikl 2 > Noatikl 3; Mixtikl 6 > Mixtikl 7; Liptikl 1 > Liptikl 2), meaning the older version is retired*;
- The app evolves into a new app altogether that sports a new name (Noatikl, Mixtikl, Liptikl, Tiklbox for iOS > Wotja for iOS), meaning the older version is retired*.
Even though we are sad when we have to retire an app, we do it because it is like pruning - old wood needs to be cut out for the new wood to have space to grow. That a developer does it is a good sign that they care. So far we have luckily never had to let an app die altogether; we have always found a route forward for it, however challenging that might have been.
However, if a developer can't afford to continue developing/maintaining an app and/or loses interest in it then it will just wither and die. The App Store is festooned with those kind of apps, now called zombie apps. Unless a developer actually removes such an app from sale (most don't) then it is hard to tell if the app is dead or not - no one knows if it will ever come back to life. This is why we remove old apps from sale, such as those below.
Tip: You may prefer to refer to the last PDF User Guide that was made available as the online User Guides linked to below are very likely to suffer from broken links, formatting and other issues.