Versions 2.9.8 (free) and 1.5.13 (premium) added a new filter, relevanssi_post_ok, which can be used to add support for membership plugins where there is a need to restrict certain posts from certain users.
For Premium version 1.8 and up
The filter passes two parameters: a boolean value (defaults to true) and the post ID. The filter wants the boolean value back. Make it true if the post can be shown and false if the user is not allowed to see the post.
How your function ends up with the response is up to you, but if you need to check the post status, I suggest you use relevanssi_get_post_status() instead of regular get_post_status(), as the Relevanssi function already has all post statuses cached. For post types, you can use relevanssi_get_post_type(). Both take post ID as an argument and return the obvious result.
For free Relevanssi and Premium < 1.8
The filter passes only one parameter, the post ID, and wants a boolean response — true if the post is ok to show, false if not. This has a problem of not being able to chain multiple actions, which is why this was changed in later version.