Following are my code that return expiry time of token and some other login info.
include_once('vendor/copyleaks/php-plagiarism-checker/autoload.php');
use Copyleaks\Copyleaks;
$copyleaks = new Copyleaks();
$loginResult = $copyleaks->login('xxxxxxxx@gmail.com','My-Api-Key Here');
echo json_encode($loginResult);