We launched an app with $500k annual revenue, and then Apple copied it

The key question at that time was: Was there a way to automatically determine how much time a user spends on Facebook or Instagram and block those apps once a limit was reached? We could set up a VPN service and analyze the traffic passing through our servers to learn which social media services mobile devices were communicating with, and using this data we could estimate the time spent on different services and block access to them when users exceeded their self-determined limits. Since Sense was a background process and performed most of its functions with very little interaction with the user (tracking time spent on social media, displaying notifications about exceeding the limit, blocking access to monitored apps), we could not use app launch as the reference event for retention.

Source: gopractice.io