I think I found the function to get the post permission on members plugin.
try with members_can_current_user_view_post( get_the_ID() )
and you start with this code :
<?php $permission = members_can_current_user_view_post( get_the_ID() );
if( $permission == 1 ){
the_title();
}else{
echo "locked post";
}
?>
maybe it useful for another