Platform-as-a-service (PaaS) is a kind of cloud computing service in which, rather than having to build and maintain their own infrastructure, a client is able to develop, run, and manage applications on a platform that is provided by a third-party provider. The provider hosts both software and hardware, freeing the client from having to install and handle them in-house.
I would rate the cost 3 out of 5. There are additional costs other than licensing fees.