Paid Memberships Pro: Hide Old Posts From New Members except specific categories.

hide_old_posts_from_members.php

<?php

/**
 * Hide old posts from new members, except for specific categories.
 */
add_filter( 'pmpro_has_membership_access_filter', 'hide_old_posts_from_members', 10, 4 );
function hide_old_posts_from_members( $hasaccess, $thepost, $theuser, $post_membership_levels ) {
	global $wpdb;

	// if PMPro says false already, return false
	if ( ! $hasaccess ) {
		return false;
	}

	// If the post has the category "tutorials", allow access.
	if ( has_category( 'tutorials', $thepost ) ) {
		return true;
	}

	// if the post doesn't require membership, allow access
	if ( ! $post_membership_levels ) {
		return true;
	}

	// okay, this post requires membership. start by getting the user's startdate
	$startdate = pmpro_getMemberStartdate( $theuser->ID );

	// no startdate? return false
	if ( empty( $startdate ) ) {
		return false;
	}

	// if the startdate is before the post date, return true
	if ( $startdate < strtotime( $thepost->post_date ) ) {
		return true;
	} else {
		// in this case we want to also tweak the message shown
		add_filter( 'pmpro_non_member_text_filter', 'swap_old_posts_member_text' );
		return false;
	}
}
function swap_old_posts_member_text( $s ) {
	$s = 'This content was published before your membership started.';
	return $s;
}