What do Spotify, Todoist, Evernote and LinkedIn have in common? They all run under a freemium business model. The freemium model became an especially popular business model in the digital startup, newspaper and service scene since the emergence of Software-as-a-Service. The problem is, how do you make sure you do not offer too much for free, but still enough to attract premium subscriptions? I will show you step by step how you can evaluate and improve your freemium business model using survival and hazard models.