Lets start with the Community credits.

while you start offering comments, you will start receiving community credits of which you can use them to request comments on your website too .

certificaton process
once you start offering comments there is a target that you have to achieve so as to be certified as a commenter that is issue 50 comments within the first 30days with a rate of over 80% approval once you achieve this, you get certified automatically and now you can start earning some cash credits.

Once the approval is made the next comments you get a community credit followed by a cash credit consecutively, each cash credit is worth 0.5$ each, so the more you offer comments the more you earn.

lost commenter certification

if you stop offering comments you might loose your certification and thus stop earning through comments and once this happens, you can still regain your certification by offering more comments to achieve the target again, and while you achieve the 50+ comments within 30 days with over 80% approval, then automatically you regarding your certification, it is pretty easy to do that, so don't give up keep on offering comments to regain your certification.