Code to get PMPro Gift Levels and PMPro Set Expiration Dates to play together nicely.

pmpro_after_checkout_gift_level_set_expiration.php

<?php

/*
	This should allow you to set a calendar end date to work with Gift Memberships.
	Use at your own risk.
	If a gift level is purchased, copy the set expiration date if applicable.
	Must have Gift Membership Add On and with Set Expiration Date being used.
*/
function pmpro_after_checkout_gift_level_set_expiration($user_id)
{
	global $wpdb, $pmpro_level, $pmprogl_gift_levels;
	
	//only if the set expiration dates plugin is active
	if(!function_exists('pmpro_saveSetExpirationDate'))
		return;

	//check if we're checking out for a gift level
	if(!empty($pmprogl_gift_levels) && !empty($pmpro_level) && !empty($pmprogl_gift_levels[$pmpro_level->id]))
	{
		//get last gift code
		$gift_codes = get_user_meta($user_id, 'pmprogl_gift_codes_purchased', true);
				
		//not sure why we wouldn't find any, but just in case
		if(empty($gift_codes))
			return;
			
		//get the last one
		$last_gift_code = end($gift_codes);
				
		//again, just in case
		if(empty($last_gift_code))
			return;
		
		//look for a set expiration date
		$set_expiration_date = pmpro_getSetExpirationDate($pmprogl_gift_levels[$pmpro_level->id]['level_id']);
				
		//save it
		if(!empty($set_expiration_date))
		{			
			pmpro_saveSetExpirationDate($pmprogl_gift_levels[$pmpro_level->id]['level_id'], $set_expiration_date, $last_gift_code);
		}
	}	
}
add_action('pmpro_after_checkout', 'pmpro_after_checkout_gift_level_set_expiration', 20);