The Revolution Slider is a plugin, it will not be removed when you update your Alora Theme. It will not be affected. We will not be providing any updates for Revolution Slider. Take care, do not accidentally delete the plugin, you will not be able to install back from the Theme admin.
In the latest Alora Theme, there will not be a message to ask you to install Revolution Slider, because the packed zip file is removed from the Theme zip file.
Any client whom had not used Alora Theme before, will not be able to install Revolution Slider from within the Theme admin. They will need to purchase from the plugin authors.
Hope this clarifies your doubts.