Extend Expiration Dates For Renewed Memberships in Paid Memberships Pro

gistfile1.php

/*
	Important note! This code is included in PMPro versions 1.5.7 and later. 
	Adding this code will add 2x the number of days to the end of the subscription.
*/
//if checking out for the same level, add remaining days to the enddate
function my_pmpro_checkout_level($level)
{		
	global $pmpro_msg, $pmpro_msgt;

	//does this level expire? are they an existing user of this level?
	if($level->expiration_number && pmpro_hasMembershipLevel($level->id))
	{
		//get the current enddate of their membership
		global $current_user;
		$expiration_date = $current_user->membership_level->enddate;
		
		//calculate days left
		$todays_date = time();
		$time_left = $expiration_date - $todays_date;
		
		//time left?
		if($time_left > 0)
		{
			//convert to days and add to the expiration date (assumes expiration was 1 year)
			$days_left = floor($time_left/(60*60*24));
			
			//figure out days based on period
			if($level->expiration_period == "Day")
				$total_days = $days_left + $level->expiration_number;
			elseif($level->expiration_period == "Week")
				$total_days = $days_left + $level->expiration_number * 7;
			elseif($level->expiration_period == "Month")
				$total_days = $days_left + $level->expiration_number * 30;
			elseif($level->expiration_period == "Year")
				$total_days = $days_left + $level->expiration_number * 365;
			
			//update number and period
			$level->expiration_number = $total_days;
			$level->expiration_period = "Day";
		}
	}
	
	return $level;
}
add_filter("pmpro_checkout_level", "my_pmpro_checkout_level");