Paid Memberships Pro: Hide Old Posts From New Members

hide_old_posts_from_members.php

/*
	This code will create a content filter for all pages and posts to remove access to posts that were published before a member's join date. Only posts or pages which require membership will be hidden. Note that pages and posts that require membership will still be hidden from non-members regardless of the publish date.

	The params passed are:
		$hasaccess - (bool) what PMPro thinks about whether the user has access
		$thepost - (post object) the post being checked, usually the current post
		$theuser - (user object) the user being checked, usually the current user
		$post_membership_levels - (array of levels) the levels this post requires (if any)
*/
add_filter("pmpro_has_membership_access_filter", "hide_old_posts_from_members", 10, 4);
function hide_old_posts_from_members($hasaccess, $thepost, $theuser, $post_membership_levels)
{
	global $wpdb;
	//if PMPro says false already, return false
	if(!$hasaccess)
		return false;

	//if the post 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;
}

This recipe is included in the blog post on "Hide Previous Content From New Members" at Paid Memberships Pro here: https://www.paidmembershipspro.com/hide-previous-content-from-new-members/