In December, The New York Times featured Susan Miller's Astrology Zone app in a story about how popular apps are trying to find a revenue stream through paid subscriptions. In this Case Study, we interviewed Miller to get the actual data and stats, which included a 1.3% conversion rate. Read on to discover the pros and cons of the mobile app subscription industry, from awesome member engagement tactics like push notifications to a lack of control when it comes to renewal marketing. Plus, discove...