This plugin is free!
This plugin is not currently on the WordPress.org repo, but we plan to make it available there in the future.
The plugin is available on packagist: https://packagist.org/packages/wp-graphql/wp-graphql-smart-cache.
This plugin was built to work in WordPress on any WordPress host.
The Network Cache functionality requires specific functionality from the host's network cache layer to work properly.
We've partnered with WP Engine to get this functionality working for WP Engine customers, but we hope to see more hosts support GraphQL caching and Cache Invalidation at the network cache level.
We have a hosting guide for hosts that are interested in providing support.