The freemium app model is a monetization strategy for mobile apps where app developers publish their apps for free of charge and monetize them with subscriptions or in-app purchases. Most of the mobile games use the freemium model to reach a wide range of users for free and then generate revenue from a small portion of those users. 

In order to monetize an app with a freemium model successfully, app publishers need to design in-app purchase mechanisms very carefully. Freemium model is a strategy based on the current users so user experience and premium content strategy should satisfy the needs of loyal users. 

Learn more about the freemium model.