Since mobile application market was open, developers have been seeking for strategies to maximize their profit. However, there is little research on user behavior of mobile applications for its short history. In this study, we conducted an exploratory study on mobile application users with actual usage data of Weather On. The result indicates positive relation between the premium conversion rate and the logarithm of the market wealth. It is observed that most of the users take only a short time to make a purchase or dropout decisions. Also, we suggest that push message can induce user responses in a positive or negative way.