Freemium
Freemium, a portmanteau of the words "free" and "premium", is a pricing strategy by which a basic product or service is provided free of charge, but money (a premium) is charged for additional features, services and virtual (online) or physical (offline) goods that expand the functionality of the free version of the software. This business model has been used in the software industry since the 1980s and is closely related to tiered services.