If they've truly changed, their reward is from the universe in the form of a more peaceful and fair existence. You are not the reward fairy. You are not a vending machine where they put in an apology and get a bag of no-consequences.
Madness string 98159
Time keeps ticking. Even if something seems like it will last forever, time will still make it seem like nothing. If it takes 10^65 years for something to die out... time will eventually get there and go on.