How do I update app installed from 3rd-party with Google Play Store's version? I want to update my WhatsApp to be able to use the calling feature. I've used a third party app to update WhatsApp till now. How do I update from Play Store, or will it only happen automatically and not manually?
The call feature is available in WhatsApp-2.12.5.

The Google Play Store should show you the latest version (If Notification Checked)


  How do I update from Play Store, or will it only happen automatically
  and not manually?


This is only available, when the below option is enabled: if this option is disable, you need to download manually.



As you can see in above option, if there is an update it will be shown in a notification.