Filters the message displayed when the post is viewed by a visitor who does not have a WordPress user account. By default, this is set to display the text configured on the Memberships > Advanced Settings page.
apply_filters("pmpro_not_logged_in_text_filter", string stripslashes(pmpro_getOption("notloggedintext")));
SourceView in Source Code
Related Articles and Recipes
Customizing the Message for Non-Members on Membership Protected Content By Kimberly Coleman