WordPress plugin not automatic update

It must be done in wp-config.php file. There is two ways to accomplish this.

  1. Defining a constant or
  2. Adding a filter.

lets check WordPress codex (http://codex.wordpress.org/Configuring_Automatic_Background_Updates) guideline in “Plugin & Theme Updates via Filter” section. That must fulfill your need.

Let me know if it works!

Cheers! 🙂