For all the included plugins, Visual Composer too, we have purchased an Extended License that let us bundle the plugins with the theme.
This means they can be used by any one purchasing our theme as long as they use the version included in theme folder. You don’t need to purchase any other license for the plugins that are included in the theme. But you can not update it on your own terms with this type of licence. The rules of the marketplace do not allow us to give the plugin activation code but you can use the existing version without any problem. We update frequently all theme plugins to their latest versions in every theme release or in case when an urgent update is needed. So they are always fully compatible with the current theme version.
If you want to buy a license by yourself this is allowed. You have to buy a new single license but we thought that this isn’t needed because the version included works perfectly.
You are free to make the choice that best fits your needs.