Hello,
Thank you for getting in touch with us. That is a good question and we get it all the time.
Google does not honor Meta Keywords for quite a long now so we never added them to the plugin.
You can read more about that here:
https://webmasters.googleblog.com/2009/09/google-does-not-use-keywords-meta-tag.html
Hope that helps. If you have any further question(s), please let us know. Thank you.
Hello,
Since we did not hear back from you for 15 days, we are assuming that you found the solution. We are closing this support ticket.
If you still need assistance or any other help, please feel free to open a new support ticket, and we will be more than happy to assist.
Thank you.