$Package->setExternalKey($your_subscription_id);
// This is for our data usage
$LineItem = new ChargeOverAPI_Object_LineItem();
$LineItem->setItemId(13);
$Package->addLineItems($LineItem);
// This is for our extra # of devices
$LineItem = new ChargeOverAPI_Object_LineItem();
$LineItem->setItemId(14);
$Package->addLineItems($LineItem);
$resp = $API->create($Package);
if ($resp->response->id) {
    // Created the package!
    // Now, every day you want to push new usage to it
    // Get the package
    $resp = $API->find('package', array('external_key:EQUALS:' . $your_subscription_id));
    $resp = $API->findById('package', $resp->response[0]->getPackageId());
    $Package = $resp->response;
    $Lines = $Package->getLineItems();
    foreach ($Lines as $Line) {
        if ($Line->getItemExternalKey() == 'data') {
            // @todo Go fetch the usage from your database for the # of gigabytes
            $usage_data = 5;
            // 5 gigabytes
        } else {
            if ($Line->getItemExternalKey() == 'devices') {
                // @todo Go fetch the usage from your database for the # of devices
                $usage_data = 9;
                // 9 devices
            }
        }
        // Push the usage
<?php

header('Content-Type: text/plain');
require '../ChargeOverAPI.php';
//This url should be specific to your ChargeOver instance
$url = 'http://dev.chargeover.com/api/v3';
//$url = 'https://YOUR-INSTANCE-NAME.chargeover.com/api/v3';
$authmode = ChargeOverAPI::AUTHMODE_HTTP_BASIC;
$username = '******';
$password = '******';
$API = new ChargeOverAPI($url, $authmode, $username, $password);
//Find a customer by the ChargeOver customer ID
$resp = $API->findById('customer', '8');
/*
print("\n\n\n\n");
	print($API->lastRequest());
	print("\n\n\n\n");
	print($API->lastResponse());
	print("\n\n\n\n");
*/
if (!$API->isError($resp)) {
    $customer = $resp->response;
    print 'SUCCESS! got back customer: ' . $customer->company;
} else {
    print 'There was an error looking up the customer!' . "\n";
}
<?php

header('Content-Type: text/plain');
require '../ChargeOverAPI.php';
//This url should be specific to your ChargeOver instance
$url = 'https://dev.chargeover.com/api/v3';
//$url = 'https://YOUR-INSTANCE-NAME.chargeover.com/api/v3';
$authmode = ChargeOverAPI::AUTHMODE_HTTP_BASIC;
$username = '******';
$password = '******';
$API = new ChargeOverAPI($url, $authmode, $username, $password);
//Find a customer by the ChargeOver customer ID
$resp = $API->findById(ChargeOverAPI_Object::TYPE_INVOICE, 2720);
if (!$API->isError($resp)) {
    $Invoice = $resp->response;
    print_r($Invoice);
    //print_r($Invoice->getLineItems());
    //print_r($Invoice->getLineItems(1));
    //print($Invoice->getCustomerId());
} else {
    print 'There was an error looking up the invoice!' . "\n";
}