The Meta Keywords features are disabled by default in All in One SEO. This is because meta keywords hold no value in today's SEO. This post from Google explains why they no longer use them.
However, the Russian search engine Yandex does still use them so this article is meant for our Russian users.
We have an FAQ about Meta Keywords here.
In This Article
Enabling Meta Keywords Settings
If you're targeting Yandex then you can enable these features by clicking on Search Appearance in the All in One SEO menu and then going to the Advanced tab and setting Use Meta Keywords to Yes.
Adding Meta Keywords to Your Content
This will enable the Keywords field in the AIOSEO Settings on the Edit screen for your content. You can add meta keywords to any content such as a post, page, category, tag, etc. by editing the content, and clicking on the Advanced tab in the AIOSEO Settings section.
Type your keyword in the Keywords field and press Enter. Repeat this to add more keywords.
To delete a keyword, click the X next to the keyword.
Using Categories and Tags as Meta Keywords
In addition to adding your own meta keywords, All in One SEO can also generate keywords from the categories each post is assigned to or from the tags added to a post.
To enable this, click on Search Appearance in the All in One SEO menu and then go to the Advanced tab and set Use Categories for Meta Keywords and/or Use Tags for Meta Keywords to Yes.
Automatically Generating Meta Keywords on Your Blog Page
Finally, All in One SEO can automatically generate the meta keywords for your post archives from the keywords you've set on the posts in that archive.
To enable this, click on Search Appearance in the All in One SEO menu and then go to the Advanced tab and set Dynamically Generate Meta Keywords to Yes.
This setting will generate the keywords for the homepage (when set to display latest posts), the static Blog page, category and tag archives, and date and author archives from the keywords you've set on the posts within that archive.