Exemplo de criação para realizar notificação de transação para assinatura ou pedido

1-Notification.php

<?php 

namespace Transactional;

abstract class Notification
{
      protected $customer;
      protected $order

      public function __construct($customer, $order)
      {
	       $this->customer = $customer;
               $this->order = $order;
      }

      abstract public function send();
}

2-SubscriptionCreateNotification.php

<?php 

namespace Transactional;

class SubscriptionCreateNotification extends Notification
{

	public function send()
	{
		//Dispara o email
	}
}

3-SubscriptionPaidNotification.php

<?php

namespace Transactional;

class SubscriptionPaidNotification extends Notification
{

	public function send()
	{
		//Dispara o email
	}
}

4-NotificationSubscriptionManager.php

<?php 

namespace Transactional;

class NotificationSubscriptionManager
{
	private $notifications = [
				 'PAID' => Transactional\SubscriptionPaidNotification::class,
				 'CREATE' => Transactional\SubscriptionCreateNotification::class,
	                         ];

	private $customer;
        private $order;
	
	public function __construct($customer, $order)
	{
	      $this->customer = $customer;
              $this->order = $order;
	}


	public function add($status, $class)
	{
		$this->notifications[$status] = $class;
	}

	public function submit($status)
	{
		$class = $this->notifications[$status];

		$obj = new $class($this->customer, $this->order);
		$obj->send();
	}

}

5-index.php

<?php 

use Transactional\NotificationSubscriptionManager;

$customer = ['id' => 123, 'name' => 'Aluno', 'email' => 'aluno@conta.com.br'];
$order = ['order_subscrition_id' => 12, 'customer_id' => 123];

$status = 'PAID';

$notification = new NotificationSubscriptionManager($customer, $order);
$notification->submit($status);