Well, there are several. I am not sure where to start. But I guess the most fundamental problem (to me) is this: at the core of the app are "implemented algorithms". Right? What is exactly "implemented algorithms"? They are just "software". The app is just ill-defined at its core. If you are selling software, then call it software.

Another thing is. Implemented algorithms are useless since they solve no real-world problems. For example, take an implementation of Dijkstra's shortest path. No real-world problem can directly use this implementation. It will have to be modified and adapted to a specific situation. This means customers will have to figure out somebody else's codes and modify it. Why don't they simply write it out themselves while consulting a classic algorithm textbook, instead of buying it?