Plz check how they monitor when people are using the app, they are reminding with email, online-offline notifications. The way they encourage learners, that boost people to continue. In this app, get streak notification once inside the app - whats the point ? Need that when we are forgetting to come to the app. In every level Duolingo having kind of meaningful conversation, notification, message to guide, encourage to continue and for this app - no other encouragement can be bigger than preparing for Akhirah.. plz analyze duolingo - that should tell you all. Retention of the users there are staggering .. lazy, irregular people like me continuing that for lasy 156 days !!! There are many in my company duoing that. May Allah help. Jajakallahu khairan.