Adds the last name tag - {donor_last_name} - to the GiveWP PDF Receipts add-on

custom_pdf_receipt_last_name.php

<?php
function custom_pdf_receipt_last_name( $template_content, $args ) {	
	$donor_last_name  = isset( $args['payment_meta']['user_info']['last_name'] ) && $args['payment_meta']['user_info']['last_name'] !== '' ? $args['payment_meta']['user_info']['last_name'] : __('Not found', 'give');
	$template_content = str_replace( '{donor_last_name}', $donor_last_name, $template_content );
	return $template_content;
}

add_filter( 'give_pdf_compiled_template_content', 'custom_pdf_receipt_last_name', 999, 2 );