You can keep track of how many images you have killed and how many more kills you can make, by clicking the information icon in the top right of the page. This brings up your summary for this production.

A gif of the Image Approvals platform, showing how to find the summary box containing information on each user's kill and image counts.
 You can also see a running total of your solo and group kills when viewing individual images. This automatically updates whenever you kill or unkill an image. 
A screenshot of the Image Approvals platform, showing the tracking of solo and group image kills.
Image Approvals online platform