Gets an array containing of all the payment IDs for a particular download using the get_log_ids() function

gistfile1.php

<?php
/**
 * Get array of payment IDs
 * 
 * @param int $download_id Download ID
 * @return array $payment_ids
*/
function get_payment_ids( $download_id = '' ) {
	// these functions are used within a class, so you may need to update the function call
	$log_ids = $this->get_log_ids( $download_id );

	if ( $log_ids ) {
		// create $payment_ids array
		$payment_ids = array();

		foreach ( $log_ids as $id ) {
			// get the payment ID for each corresponding log ID
			$payment_ids[] = get_post_meta( $id, '_edd_log_payment_id', true );
		}
		
		// return our payment IDs
		return $payment_ids;
	}
	
	return null;
}