shareasale_ee3.php

<?php
//* Please do NOT include the opening php tag, except of course if you're starting with a blank file

function espresso_track_successful_sharasale($payment_data){
    $amount = $payment_data['total_cost']; 
    $tracking = $payment_data['txn_id']; 
    $url = 'https://shareasale.com/sale.cfm?';
    $url .= 'amount=' . $amount . '&';
    $url .= 'tracking=' . $tracking . '&';
    $url .= 'transtype=sale&merchantID=73676';
    $html = '<img src="' . $url . '" width="1" height="1">';
    print($html);
}
add_action('action_hook_espresso_track_successful_sale','espresso_track_successful_sharasale');