When you purchase a Litho theme from ThemeForest, there are a few premium plugins available to use for free as part of Litho theme. Your Litho theme purchase includes premium plugins like Revolution Slider that you can use for free and you should ignore the license activation notice for those plugins.
Yet, this purchase does not give you an individual license right to use Revolution Slider and so you cannot receive direct updates of these premium plugins and get support from those plugin authors.
New plugin updates will only issue when we release new updates on Litho theme. Whenever we update the Litho theme, the latest version of Revolution Slider will be updated for free. So, you do not need to buy your own license to use these plugins in Litho theme.
We will make sure that we test plugins to give certain surity of no bugs that will conflict with our own theme update. We will also test the new theme version before releasing them to you.
Note: Slider Revolution plugins do not allow users to use their own default template/slider libraries in theme bundled plugin version, if you want to use their default templates then you will need to purchase the plugin separately and activate the license to unlock their library.