Churn rate is the number of customers or subscribers who stop using an app during a given time period, app churn impacts user acquisition and lifetime value.
There are many factors, which make users stick with an app, such as, a bug free experience, a great UI or simply a unique service. Most developers want customers to become loyal users, the challenge is how to know what customers are feeling and how to establish accountability for the customer experience.
NPS or Net Promoter Score is a metric, used widely to measure customer satisfaction, and acts as a leading indicator of growth. If your apps NPS is higher than those of your competitors, you will likely outperform them.