The old pricing is never coming back, just to be clear. However, if you bought the one time (lifetime) license at $97, you still have lifetime access to the original version of the software you bought. However, if you want the new/upgraded features (like KC scores), you need to buy into a new plan. If you still have questions, contact me or Long tail pro support at longtailpro com / support
Analyze Keyword Difficulty – Targeting difficult keywords with the highest competition is not always the best idea. The SEMrush Keyword Difficulty tool helps you determine keywords’ difficulties. By indicating a particular keyword’s percentage of difficulty, this tool helps you estimate how easy it would be to seize your competitors’ organic positions in the SERPs.
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.