Compared to desktop usage patterns, mobile apps tend to see more frequent sessions but significantly lower session lengths. For example, a product that has both a desktop and a mobile presence might see desktop users visit 10-20 times a month for session lengths of over 10 minutes on average, whereas on mobile they might see users visit 30-50 times a month for less than 60 seconds at a time.
Another difference you’ll see is that people will visit hundreds of websites in a month on desktop, but their bandwidth for apps is much more limited. On mobile, despite the fact that there are millions of offerings in the app stores, the average consumer only uses about 15-20 different apps per week on a regular basis. There’s a limit on both the real estate on a mobile user’s home screen and their capacity for adopting new apps for habitual use.
Thus for many types of mobile apps, the holy grail is to become a daily habit for users. For your app category, you want to be the “go-to” app that users depend on. Aim to get your users to come back every day, maybe even multiple times a day, in order to have a shot at broad long-term retention. A popular metric for measuring retention in the mobile games industry is DAU / MAU, or daily active users divided by monthly active users, and I highly recommend that consumer-facing mobile app developers keep track of that metric as well.