UserKey provided by RChilli is a specific id which is unique for every client. In case if there are multiple user for a client and each user need a specific identification, then in that case different SubUser Ids can be assigned to each user.
When you have multiple SubUser Ids then in Logs you can get these Parsing Logs as per SubUser Id.
Kindly follow the article to get the parsing logs How Can We Track Our Parsing Usage? – RChilli HelpDesk