In recent years mobile games have become a major part of the mobile market since gaming apps generate a major amount of the platforms revenue. Whilst different business models have been used - free to play seems one of the most promising to monetize games in the mobile market. Yet, this new concept of monetizing digital content has not obtained much attention of researchers. One research gap is the prediction of users purchasing behavior, as it is a major challenge for practitioners as well as for researchers and of vital importance for managing marketing expenses and designing game mechanics. In this paper we use an existing prediction model for purchasing behavior to analyze its applicability in the mobile market. We use two data sets from free to play games to train and test this well-known model. We can show that existing models, even though they are designed for the same type of customer relationship, struggle with the case of free to play. We show detailed information on the model performance and conclude that because of the unique purchasing behavior in free to play models should be redesigned or the process of application should be more structured.