It looks like you're new here. If you want to get involved, click one of these buttons!
You are welcome. This question is meant to be asked before building the app, moneytizing an app is a whole lot of work on its own. Maybe if you can post the apps here, you can get advice on this question.
Also, a general common way to monetize most apps nowadays is to use Google Admob (Show Ads in the App and get paid per click)