Allow non-members temporary access to restricted PMPro Content until a certain date.

allow_non_members_access.php

<?php

/**
 * Allow temporary access to all restricted content for non-members until a certain date.
 * Add this function below to your PMPro Customizations Plugin - https://www.paidmembershipspro.com/create-a-plugin-for-pmpro-customizations/
 */
 
 
function pmpro_allow_temp_access_for_non_members($hasaccess, $mypost, $myuser, $post_membership_levels){

	// Do not affect existing memberships access to posts.
	if( pmpro_hasMembershipLevel() ){
		return $hasaccess;
	}

	$end_date = strtotime( date( '2017-12-31' ) ); //change this date value. Format ( Y-m-d ).
	$today = strtotime( date( 'Y-m-d' ) );

	//get the difference in date.
	$diff = $end_date - $today;
	
	// If end date is today or earlier, grant access - if today > end date, return false.
	if( $diff >= 0 ){
		$hasaccess = true;
	}else{
		$hasaccess = false;
	}

	return $hasaccess;
}
add_filter( 'pmpro_has_membership_access_filter', 'pmpro_allow_temp_access_for_non_members', 30, 4 );

This recipe is included in the blog post on "Lock or Unlock Posts Based on Age and Post Date" at Paid Memberships Pro here: https://www.paidmembershipspro.com/lock-unlock-posts-based-age-post-date/