Will Norris

Comment Saver temporarily stores the content of comments in a browser cookie 
just in case something goes wrong while submitting the comment. For example, 
if the user forgot to include their name and email address and those fields are 
required, the comment may be lost on some browsers. When the user returns to 
the comment form, Comment Saver will automatically populate the comment box if 
the cookie is still set. It will remove the temporary cookie once the comment 
has been successfully submitted, or after one hour.

Comment Saver

Save comment content in a cookie in case something goes wrong while posting.

Comment Saver vs Spam protection, Honeypot, Anti-Spam by CleanTalk