This option is for users who have purchased this plugin individually.
When you purchase a theme from ThemeForest that bundles Visual Composer and Revolution Slider, you are free to use these Premium plugins with the theme. However, your theme purchase does not give you individual Visual Composer and Revolution Slider licenses that allow you to activate or download these plugins as you wish. Activation doesn’t mean the plugin will not work but only that you cannot receive direct updates. Please don’t worry if you see warning messages about the plugin license activation.
To update you need:
Navigate to the Plugins menu in your WordPress admin area.
Deactivate Plugin, delete it
Go to Install Required Plugins
Upload and install the new version
Activate Plugin .