We will only show the basics you need since the code is owned by Blesta and not for public release...

license.php
Must start with the plugin name: eg:

<?php

class BlestaCMSLicense {

And re-declare the class to stop conflicting:

            require_once dirname(__FILE__) . DIRECTORY_SEPARATOR . "license_manager.php";
            $this->LicenseManager = new BlestaCMSLicenseManager($path_to_phpseclib, $signature_mode, $signatures, $install_path);

license_manager.php
Must start with something like:

final class BlestaCMSLicenseManager
{