Hi,
Since you are already a subscriber to the Professional Toolset, you have access to MSTC. MSTC can be purchased as a stand alone product, but we included the functionality to all Professional Toolset Users. That is the reason you can't trial it. To access MSTC, you can select from the following:
http://www.dnsstuff.com/tools/ - the second tile at the top
http://www.dnsstuff.com/tools/mstc/ - direct link
Best,
anish