They sent her a "unicorn license" certificate with her name on it, signed by the animal control director. They also sent a unicorn stuffed animal with a "permanent unicorn license" tag. (Here's their Facebook post.)
They did give her a few rules though: If she ever finds a unicorn, she has to comply with all caretaking regulations . . . give it "access to sunlight, moonbeams, and rainbows" . . . and polish its horn at least once a month with a soft cloth.