The word freemium is a combination of the words free and premium.  It describes a business model in which you give a base product away for free to a large group of users and sell premium products to a smaller fraction of this user base. In the Freemium model a service (usually a self-service, software-based service) is provided free to users with basic features, and then additional, more advanced features can be “unlocked” (ie made available) by purchasing an upgraded license fee. The concept of providing a freemium service is that it enables customers to try out the product or service at low or no risk to see if they like it before they invest in a chargeable version.