Can you please post a valid link, this one doesn't work anymore.
How does the support system work exactly for payed support? Clients might wanna use it, so there should be a direct way to use it without the need to provide a license key every time.
For a severe issue with mixed library version of Plesk I recently opened a ticket with the add-on-support. The case was solved smoothly by a highly motivated, knowledgable support team member. Awesome support and still worth every single Cent! Good to know that there is a safety net if my "wisdom" just isn't enough to solve a case do-it-yourself.