I could not see anywhere saying this is a tool requires paid monthly membership?

Mongols tool

All useful features behind paid wall. Don't bother.

With the subscription, it has a ton of nice features, probably some of the best SEO / backlink tools for the price.

Works just as good as the Chrome one.

Really this is a nice extension, which a seo expert is very helpful and a lot of time saving. Thanks for great tool.

Doesn't work. Stuck in a loop of "you have to register" and not being able to recognize my premium login. Redirects to their website where I'm already logged in, while the addon stays logged out.

nice seo tool

Excelente complemento para firefox!

It's PAID plugin. It give you FREE FIVE Keyword, FREE FIVE SERP and FREE FIVE website lookup(DA, Trust Rank, etc..) details only. So, be wise and search other plugin for your SEO needs. You have to REGISTER an ACCOUNT to use all services.

it amazing tool with awesome interface. I most like its features which includes the DA, PA metric. This is the only extension for Firefox browser which includes a ton of useful features

Very sophisticated SEO options, easy handling, good overview about key metrics.