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.
If you don't know the difference between head terms and long-tail keywords, let me explain. Head terms are keywords phrases that are generally shorter and more generic -- they're typically just one to three words in length, depending on who you talk to. Long-tail keywords, on the other hand, are longer keyword phrases usually containing three or more words.
What I really like about them is extensive detail including the keyword difficulty. Ahrefs uses clickstream data to also show how many clicks you will get from the search engine. This is very useful after knowledge graph integration, as many keywords may have huge traffic but they hardly get any clicks from the search engine. Reason being, they get answers directly from the Google search result. Example of one such query is: “birthdate of any celebrity”
Settings. This tiny gear icon on the right upper corner is where you can ask support for “Help”, toggle on or off the help icons; manage “User Accounts” (you need to enter your Google AdWords credentials when the software is run for the first time plus your Moz API details too, which are free to get since LTP uses a both AdWords and Moz’s data); set the “Data Fetching Speed”; and check the “Show Runtime Error” and “Show Debug Panel” in the “Debug” section (which can be very helpful when there’s something wrong with the tool or with your Google AdWords account).
The limit on manual keywords could be higher.  I personally wish we could input 10,000 keywords at a time, instead of 200.  However, I understand the costs that Long Tail Pro has to maintain each time a new manual keyword is input.  Not a deal breaker, I just wish the limit was higher. (To be fair, I don't think most keyword tools have a bulk manual option at all).