There are several models you can opt for.
Freemium: With this model app publishers offer mobile users to download apps free of charge to use with a limited set of features and charge them via in-app purchases for premium features, additional content, or digital goods.
In-App Purchases: One of the app monetization strategies that is particularly relevant to mobile games only is in-app currency. A typical example would be offering a mobile game users to buy via in-app purchase a set of coins for them to use in the game, e.g.
Quoting Apple's description of the Subscription model: Auto-renewable subscriptions give users access to content, services, or premium features in your app on an ongoing basis. With this model, app developers can offer multiple plans with options to upgrade, downgrade and crossgrade . The major feature of this model that appeals to users is that with Subscription model developers can offer a discount for a long subscription period.
Affiliate Marketing and Lead Generation: Such time proven monetization strategy as affiliate marketing can be yet another way for app developers to monetize their mobile inventory. In a nutshell, affiliate marketing for mobile apps is about being rewarded with a commission fee for every instance when a mobile app was downloaded or specific action was taken with an app via the link placed inside your app. To make it work for you app monetization strategy, you need to choose what specific apps to promote inside your application, apps that can compliment your app for your users experience.

You can read more here: https://www.businessofapps.com/marketplace/app-monetization/research/app-monetization-models/
Besides if you do have any questions give me a call: https://clarity.fm/joy-brotonath