How do you define to view your app? 
I guess you refer to having the app opened in a focused browser tab.
You can have a Do every X seconds workflow that
- Updates a
lastFirstVisitOfDay (date)field in the User table. - Executes only if the value of the field is not a today’s timestamp.
- Increases a counter stored in
dailyAppVisits (number)of table User.
Disclaimer: Do every X seconds workflows stop executing when the User loses connection with Bubble servers under some circunstances, e.g. suffers a connection outage or hibernates the device. So, test if this is enough for your use case, otherwise you’ll need a more convoluted solution similar to what I exposed in User presence system design (user online/offline status).