If you’re using word press, get squirlly, start free and upgrade to paid only if you need to. If you are just running your own site, you may never need to. If you are managing sites for others, then you’ll probably want the paid version.
Makes YOAST and plugins of that generation look like a joke. It is not just a plugin but “talks” to the squirlly seo service database to keep you up-to-date, recommend key words and much much more. I took a site, this site, that had about 5 hits a year, up to hundreds of hits a month in about 60 days.