Most business apps turn out to have an expanding future.
They're designed for something specific. When they do it, someone says, "Hey, could we also..." or "Wouldn't it be great if..."
So most business apps always have a next, more useful and powerful version under development. If there is a lot of data, often new ways of exploring it and teasing out opportunities will become apparent, that were hidden when just gathering the data was enough of a chore. Easy data entry and access makes this happen.
The app becomes more beneficial to the business over time.
This is great news for app sellers too; in fact, it's the answer to a common question about protecting your idea from copy cats. If you've got an app that services a particular industry and you constantly develop it to better serve a wider range of your clients' needs, you'll be creating a barrier to entry. Copy cat competitors will look at how much work they have to do just to catch up – and think twice. As your customers more deeply integrate their business with your app they'll acquire quite a bit of supplier inertia; they won't want to change, even if the competitor promises a price cut.
You can get a feel for this from the site of one of our app clients, WorkPodSafety.