When you launch Vuo, if you haven't activated your license yet, Vuo will show a dialog. Click the "Activate Vuo Pro" button.
In the next dialog, follow the instructions to activate Vuo Pro.
When you click the link in the above dialog, your web browser will open. You can log in to vuo.org, if you haven't already.
You'll then see a page with an activation code for the computer you're currently using.
Copy and paste that code into Vuo's activation dialog, click the "Activate Vuo Pro" button, and you'll then be able to use the additional features in Vuo Pro.