Add !!membership_level_name!! to all email templates for Paid Memberships Pro Email Template Add On.

add-membership-level-name-email-template.php

<?php
/** 
 * Add attribute !!membership_level_name!! to all email templates for Paid Memberships Pro Email Templates Admin Editor.
 * Follow this guide to add custom code to your WordPress site - https://www.paidmembershipspro.com/create-a-plugin-for-pmpro-customizations/
 */

function my_pmpro_email_data($data, $email) {
	if ( ! isset( $data['membership_level_name'] ) ) {
		$user = get_user_by( 'email', $data['user_email'] );
		$level = pmpro_getMembershipLevelForUser( $user->ID );

		if ( isset( $level->name ) ) {
			$data['membership_level_name'] = $level->name;
		} else {
			$data['membership_level_name'] = 'N/A';
		}
	}

	return $data;
}
add_filter( 'pmpro_email_data', 'my_pmpro_email_data', 10, 2 );