Licenses to Kill

So after Parsifal wins the Nevada death race(for the 28th time according to the announcer) he wins the sclave Flower(another item to discuss but first thing's first) and 3 ''licenses to kill''.What exactly do they mean?Surely he or anyone else in that particular time doesn't need a license to kill somebody right?I mean after all he just killed 4 guys in the race and considering he has won another previous 27 races means he has killed at least another 27 men(probably more considering one car more than likely had more than 1 person in it) so why the license thing?
Also his use of the licenses give Flower her freedom?Or he jsut chooses to let her go due to her being dead weight for him?