diff --git a/src/Listeners/Base.php b/src/Listeners/Base.php
index b74340d..3f37702 100644
--- a/src/Listeners/Base.php
+++ b/src/Listeners/Base.php
@@ -1,7 +1,20 @@
 <?php
-
+/**
+ * This file implements Base.
+ *
+ * @author    Bilal Gultekin <bilal@gultekin.me>
+ * @author    Justin Hartman <justin@22digital.co.za>
+ * @copyright 2019 22 Digital
+ * @license   MIT
+ * @since     v0.1
+ */
 namespace TwentyTwoDigital\CashierFastspring\Listeners;
 
+/**
+ * This class describes a base.
+ *
+ * {@inheritDoc}
+ */
 class Base
 {
     /**
diff --git a/src/Listeners/OrderCompleted.php b/src/Listeners/OrderCompleted.php
index 80e6c01..c858c99 100644
--- a/src/Listeners/OrderCompleted.php
+++ b/src/Listeners/OrderCompleted.php
@@ -1,26 +1,35 @@
 <?php
-
+/**
+ * This class is a listener for order completed events.
+ *
+ * It updates or creates related order model so that you can show payment
+ * and bill details to your customers.
+ *
+ * @author    Bilal Gultekin <bilal@gultekin.me>
+ * @author    Justin Hartman <justin@22digital.co.za>
+ * @copyright 2019 22 Digital
+ * @license   MIT
+ * @since     v0.1
+ */
 namespace TwentyTwoDigital\CashierFastspring\Listeners;
 
 use TwentyTwoDigital\CashierFastspring\Events;
 use TwentyTwoDigital\CashierFastspring\Invoice;
 
 /**
- * This class is a listener for order completed events.
- *
- * It updates or creates related order model so that you can show payment
- * and bill details to your customers.
+ * This class describes an order completed.
  *
  * Note: "order.completed" event is works just at creation for subscription products.
- *
  * IMPORTANT: This class handles expansion enabled webhooks
+ *
+ * {@inheritDoc}
  */
 class OrderCompleted extends Base
 {
     /**
      * Create the event listener.
      *
-     * @return void
+     * @return null
      */
     public function __construct()
     {
@@ -36,8 +45,8 @@ public function __construct()
      */
     public function handle(Events\OrderCompleted $event)
     {
-        // try to find that invoice on the database
-        // if not exists then create one
+        // Try to find that invoice on the database if not exists then create
+        // one
         $data = $event->data;
         $subscription = $data['items'][0]['subscription'];
 
diff --git a/src/Listeners/SubscriptionActivated.php b/src/Listeners/SubscriptionActivated.php
index a269aa0..26d77a5 100644
--- a/src/Listeners/SubscriptionActivated.php
+++ b/src/Listeners/SubscriptionActivated.php
@@ -1,4 +1,13 @@
 <?php
+/**
+ * This file implements Subscription Activated.
+ *
+ * @author    Bilal Gultekin <bilal@gultekin.me>
+ * @author    Justin Hartman <justin@22digital.co.za>
+ * @copyright 2019 22 Digital
+ * @license   MIT
+ * @since     v0.1
+ */
 
 namespace TwentyTwoDigital\CashierFastspring\Listeners;
 
@@ -7,7 +16,8 @@
 use TwentyTwoDigital\CashierFastspring\SubscriptionPeriod;
 
 /**
- * This class is a listener for subscription state change events.
+ * This class describes a subscription activated.
+ *
  * It is planned to listen following fastspring events:
  *  - subscription.canceled
  *  - subscription.deactivated
@@ -15,13 +25,15 @@
  * It updates related subscription event.
  *
  * IMPORTANT: This class handles expansion enabled webhooks.
+ *
+ * {@inheritDoc}
  */
 class SubscriptionActivated extends Base
 {
     /**
      * Create the event listener.
      *
-     * @return void
+     * @return null
      */
     public function __construct()
     {
diff --git a/src/Listeners/SubscriptionChargeCompleted.php b/src/Listeners/SubscriptionChargeCompleted.php
index 45fc4f9..8d5ad32 100644
--- a/src/Listeners/SubscriptionChargeCompleted.php
+++ b/src/Listeners/SubscriptionChargeCompleted.php
@@ -1,5 +1,13 @@
 <?php
-
+/**
+ * This file implements Subscription Charge Completed.
+ *
+ * @author    Bilal Gultekin <bilal@gultekin.me>
+ * @author    Justin Hartman <justin@22digital.co.za>
+ * @copyright 2019 22 Digital
+ * @license   MIT
+ * @since     v0.1
+ */
 namespace TwentyTwoDigital\CashierFastspring\Listeners;
 
 use TwentyTwoDigital\CashierFastspring\Events;
@@ -14,13 +22,15 @@
  * and bill details to your customers.
  *
  * IMPORTANT: This class handles expansion enabled webhooks.
+ *
+ * {@inheritDoc}
  */
 class SubscriptionChargeCompleted extends Base
 {
     /**
      * Create the event listener.
      *
-     * @return void
+     * @return null
      */
     public function __construct()
     {
diff --git a/src/Listeners/SubscriptionDeactivated.php b/src/Listeners/SubscriptionDeactivated.php
index 83c648f..e40e438 100644
--- a/src/Listeners/SubscriptionDeactivated.php
+++ b/src/Listeners/SubscriptionDeactivated.php
@@ -1,5 +1,13 @@
 <?php
-
+/**
+ * This file implements Subscription Deactivated.
+ *
+ * @author    Bilal Gultekin <bilal@gultekin.me>
+ * @author    Justin Hartman <justin@22digital.co.za>
+ * @copyright 2019 22 Digital
+ * @license   MIT
+ * @since     v0.1
+ */
 namespace TwentyTwoDigital\CashierFastspring\Listeners;
 
 use TwentyTwoDigital\CashierFastspring\Events;
@@ -8,13 +16,15 @@
 /**
  * This class is a listener for subscription deactivation events.
  * It deactivated fastspring subscription and create another local, free one.
+ *
+ * {@inheritDoc}
  */
 class SubscriptionDeactivated extends Base
 {
     /**
      * Create the event listener.
      *
-     * @return void
+     * @return null
      */
     public function __construct()
     {
diff --git a/src/Listeners/SubscriptionStateChanged.php b/src/Listeners/SubscriptionStateChanged.php
index 28f9d63..b8d5eb6 100644
--- a/src/Listeners/SubscriptionStateChanged.php
+++ b/src/Listeners/SubscriptionStateChanged.php
@@ -1,5 +1,13 @@
 <?php
-
+/**
+ * This file implements Subscription State Changed.
+ *
+ * @author    Bilal Gultekin <bilal@gultekin.me>
+ * @author    Justin Hartman <justin@22digital.co.za>
+ * @copyright 2019 22 Digital
+ * @license   MIT
+ * @since     v0.1
+ */
 namespace TwentyTwoDigital\CashierFastspring\Listeners;
 
 use TwentyTwoDigital\CashierFastspring\Events;
@@ -13,13 +21,15 @@
  * It updates related subscription event.
  *
  * IMPORTANT: This class handles expansion enabled webhooks.
+ *
+ * {@inheritDoc}
  */
 class SubscriptionStateChanged extends Base
 {
     /**
      * Create the event listener.
      *
-     * @return void
+     * @return null
      */
     public function __construct()
     {