The first thing you will need is a REST request class. There are a few out there but due to the amazing job of explaining his implementation we would recommend the following post which includes a downloadable class. Download the RestRequest class and continue reading below. (http://www.gen-x-design.com/archives/making-restful-requests-in-php/)
API DocumentationThere are three major functions available to you via the API
https://www.clientexec.com/api/resource/reseller
Adding a new license is this easy
require_once 'RestRequest.inc.php';
$url = "https://www.licensedefender.com/api/v1/license/";
$request = new RestRequest($url, 'POST');
$request->buildPostBody(array('domain'=>'testing100.com'));
$request->setUsername('yourresellerlogin');
$request->setPassword('yourresellerpassword');
$request->execute();
Removing a license
require_once 'RestRequest.inc.php';
$url = "https://www.licensedefender.com/api/v1/license/testing100.com";
$request = new RestRequest($url, 'DELETE');
$request->setUsername('yourresellerlogin');
$request->setPassword('yourresellerpassword');
$request->execute();