Hi Gil,
Thanks for checking out Events Calendar Pro! The upgrade is pretty straightforward – all you need to do is install and activate the plugin, and then you can start using the new features. No changes to your current setup required! Once you’ve purchased the license, you’ll be able to download the plugin, which you can then upload and activate in the Plugins section of your WordPress Dashboard.
This article has some good info on getting up and running with Pro. As a premium license holder, you’ll also have access to our premium support forums, so if you get stuck or have any questions on how to use Pro, please let us know – we’ll be happy to help you figure it out!