This comes with a monthly fee though, so why have that recurring revenue drain when you can just get MS or LTP for that matter on a one off fee. They are both virtually the same in my opinion. This is the only thing that is stopping me from buying the software. If the calculation of keyword difficulty was included in the one off fee, i wouldn’t mind paying the full $97.
Long Tail Pro is a keyword research tool that helps you quickly find low competition keywords for your website. In particular, the tool is built for people doing SEO (search engine optimization) as opposed to people doing paid ads (Google Adwords PPC). I'm sure there are some advertisers that use the tool for paid ad keyword research, but the tool was built for SEO keyword research.