Update UserRegistrationService.php

There must be __FUNCTION__ instead of __METHOD__ to attach in module like;
$htUserRegistrationEvents = $e->getApplication()->getServiceManager()->get('HtUserRegistration\UserRegistrationService')->getEventManager();
$htUserRegistrationEvents->attach('verifyEmail.post', function($e) use($flash) {
	/* @var $flash \Zend\Mvc\Controller\Plugin\FlashMessenger */
	$flash->setNamespace(FlashMessenger::NAMESPACE_SUCCESS)->addMessage('Account is now active');
});