FastMember has a lot of flexibility when it comes to protecting your content. One method you can choose is used by many news sites such as the Wall Street Journal.
This shows the reader a teaser of the content and then directs them to subscribe if they want to read the rest.
This short video shows you how to do the exact same protection using FastMember.
This can be used for both free and paid subscriptions and is a great way of collecting new subscribers from your existing published content.