FDR has always been one of my favorite presidents, second maybe to Lincoln. Both were men the establishment assumed were one of them until, to their horror, they governed like they weren't. Both could trash the opposition in one breath and take the moral high ground in the next.
IANAL but there should be no need to ask consent to know when users quit the signup process. You need to say that you use cookies, yes, but unless you process personally identifiable data there is no need for informed consent.