was easily making $800 a month but we never marketed it. now it's making around $200 a month easily. It has a potential to reach $4000/month revenue with minor marketing and development effort. We have no intention to maintain this app as we are a large software development business and have other bigger things in our roadmap. Right now it's linked to 2 adsense accounts. the ones that did not upgrade the app making us $100 a month and another adsense account as well.