Mo’ Money, Mo’ Money: that’s what developers can start chanting thanks to Google finally adding in-app subscriptions to Google Play. It’s been a year since they introduced in-app billing into the now Google Play Store and it’s opened a whole new avenue of monetization for developers. In fact, 23 of the 24 top-grossing apps in Google Play use in-app billing. Naturally, the next step was to add in-app subscriptions, unlike the one-time buying model of current in-app purchases, subscriptions allow developers to sell recurring content or features on a monthly or yearly basis.