TTP v12 available

Good evening,

If I am correct, it looks like TTP v12 is available for purchase/download.

I currently use macOS 10.15.1, so TTP v12 should be fine in this regard.

The question I have is: how can I purchase the upgrade without (re)purchasing TTP v11? I currently have 11.0.5 (Build 5280).

Kindly advise.

Thank you in advance.

-Merlin