Where are you going with this? Once you agree to take the apartment, the lesase wil be preapared and the commissions are due.
But, reading between the lines here.. are you looking to go back on your own and try to get the apartment without the Realtor thinking this wll save you the commission? If that is the case you will also be liable.
Same thing if you go wth another Realtor.
What is the reason for the question?