First Click Free is a system created by Google to index and display subscription-based content in his SERPs.
Normally, search engines cannot access website content if users must register. Implementing Google’s First Click Free (FCF) allows editors to include restricted content in Google’s search index and to gain visibility.
To use the First Click Free option, editors have to configure webservers so that the registration page is not served to search crawlers (see agent name delivery).
Editors have to also let visitors from a Google search to see the full text of that indexed document without needing to susbcribe.
First Click Free is a valuable tool for newspaper websites using paywalls.