Most of our themes provide a full version of WPBakery Page Builder.
Any time the plugin is updated, you will find the latest version of the plugin in the includes/admin/plugins or config/plugins folder of the theme.
To update the plugin, upload the content of the js_composer.zip file in the wp-content/plugins/js_composer folder on your server.
If you encounter any issue, delete the folder on your server before re-uploading it to re-install the plugin.
Or even mor simple, you can delete the plugin from your WordPress plugin panel, then reinstall in by uploading the new js_composer.zip file.
We are not allowed to sell a license for this plugin inside the theme so we can't give you one.
You need to purchase a license of WPBakery Page Builder ONLY if you need auto-update and support for the plugin author.