Thanks for writing in! Bundled plugins does not need to be registered. All the updates of the plugins will be provided with Theme.co server instead. If you want to avail premium addons of the plugin and be able to update these addons, you might need to buy a separate license of the plugin to unlock the plugins advance features and functions. You can check out more about this information from here: https://theme.co/apex/forum/t/extension-convertplus/66
If you have added the Addon even without the activating the plugin, you can disable the addon first, then delete it and re install the addon again. In most cases, it will install the latest addon.
Hope this helps.