Each theme update will contain latest version for premium plugins. You need to update the theme to latest version and you will get latest updates of premium plugins bundled with your theme. These plugins can be updated automatically however they require to purchase them which you don’t need to.
For example if you are currently using WPBakery Page Builder 5.4.5 and there is new version available for WPBakery Page Builder, you have to get latest version of your theme and then go to Appearance > Install Plugins, click Update for Visual Composer plugin and you are all set.
Automatic updates for premium plugins are not available! They are only supported for users that have purchased plugin’s license. However, each theme update contains latest version of premium plugins.
Premium plugins cannot be activated with theme purchase code?!
Often users try to activate these plugins with “theme purchase code” which in fact won’t work. The reason is simple, Envato and plugin authors doesn’t allow to activate premium plugins using theme purchase code!
Each plugin has its own purchase code, and in order to activate the plugin you need to purchase a copy for each of them.
Every theme in ThemeForest works this way with premium plugins. We are allowed to re-distrubute these premium plugins with an extended license and limited rights.
Extended License covers: including the plugin in the theme, use the plugin and get latest update via theme releases only. To get automatic updates, you need to purchase the plugin. If plugin author has made a “premium feature” that requires activation, it is not granted for Extended License owners to use it, but for individual users who purchase respective plugin.