Thanks for the compliments! Conditional Logic is available as a paid extension. When we released the new version (2.0), we changed from a lite/pro plugin model to a free-core with premium extensions model. You can see that extension and all of our others at: http://wpninjas.com/downloads/category/ninja-forms/.
Oh ok! I see it now. If…sorry when I purchase the extension, can I use it on any of my sites or is it limited to just one?
You can use it on as many sites as you like. There aren’t any limitations. Also, when you purchase any extension, you get 1 month of free priority support.
For the month of March, 2013, we’re doing two cool things: 10% of our gross plugin sales go directly to the March of Dimes to help premature babies, and you can use the code #MOD75 to get an extra 20% off if you purchase 4 or more extensions. You can read more about that here: http://wpninjas.com/buy-extensions-help-babies-save-money/
We are also currently working on an extension that should be out later this week that will allow front-end editing. With it you’ll be able to create and control registration forms, login forms, allow users to edit posts/pages/custom post types, allow users to edit/delete their own Ninja Forms submissions from the front-end.