Linking an MTurk account to your TurkPrime account allows you to use TurkPrime's services for free, excluding Pro Features. If you do not have a MTurk account and design a study solely on TurkPrime, you will be charged service fees from your Lab Balance. In the case where you run a study without a MTurk account, your study is conducted through the TurkPrime Company MTurk account. Once you submit the study, it will have to be reviewed by TurkPrime and once approved we will launch the study and we will accept or reject workers. If you run the study with your on MTurk account you can launch the study at your convenience, it is free (if you don't choose any pro features), and you get to accept or reject MTurk workers' HITs.