Beyond Expectation! I do not mind extending the support. Please keep it coming more.
This cookie is set when you login to your account at VibeThemes. VibeThemes based on WordPress sets this cookie, which indicates when you're logged in, and who you are, for most interface use.
WordPress uses the two cookies to bypass the password entry portion of wp-login.php. If WordPress recognizes that you have valid, non-expired cookies, you go directly to the WordPress Administration interface. If you don't have the cookies, or they're expired, or in some other way invalid (like you edited them manually for some reason), WordPress will require you to log in again, in order to obtain new cookies.
When you comment on VibeThemes blog, they too get cookies stored on their computer. This is purely a convenience, so that the visitor won't need to re-type all their information again when they want to leave another comment.
The commenter cookies are set to expire a little under one year from the time they're set.