where do you add this code
add_action('woocommerce_order_status_completed', function($orderId) {
$order = wc_get_order($orderId);
if (!$order) {
return;
}
WC()->mailer()->emails['LMFWC_Customer_Deliver_License_Keys']->trigger($order->get_id(), $order);
}, 11, 1);