Here’s where this tool’s value really comes in: Keyword Tool has keyword research tools for multiple search engines, not just Google. If you want to do keyword research for YouTube, Bing, Amazon, the App Store, or eBay, they’ve got keyword suggestions (and data) for you. If YouTube videos, for example, are a central part of your marketing strategy, this could easily be worth the money.
How much is a keyword worth to your website? If you own an online shoe store, do you make more sales from visitors searching for "brown shoes" or "black boots"? The keywords visitors type into search engines are often available to webmasters, and keyword research tools allow us to find this information. However, those tools cannot show us directly how valuable it is to receive traffic from those searches. To understand the value of a keyword, we need to understand our own websites, make some hypotheses, test, and repeat—the classic web marketing formula.
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.