If you're currently running Studio One Professional with the included Melodyne Essential 2.x, there's a very simple solution: you can upgrade to Melodyne Essential 4 for free! All you need to do is log into you MyPresonus account, navigate to your Studio One 3 Professional downloads, scroll down to "Extra Downloads" and download the latest Melodyne Essential installer. This installer will upgrade Melodyne Essential 2 to version 4.