Once you claim them on a toon, it is permanent to that toon. If you delete the toon, the Vet Rewards are gone and still counted as used for that toon. If you move the toon to another account, you will automatically gain the Vet Rewards again after 1-year, and the Original Account will be short the one Vet Reward that the toon claimed on that account.
Yther Ore.