freemium
noun [ U ] business specialized uk/ˈfriː.mi.əm/ us/ˈfriː.mi.əm/
免费增值模式（一种商业营运模式，基本产品或服务免费，使用更高级产品或服务时则需要付费）
a way of charging for a product or service in which the basic product or service is free, but the customer pays for extra features
a freemium business model 免费增值商业模式