it could be a possibility, aeria games like the fake gamble system. because there is no luck in it, you will pay more anyway for buy any items that you want unlimited. Try to use 10 000 ap of boxes, and you will end with only 2 unlimited items.
also, if you receive 10 items which last 7 days, they will disapear the next weak, ALL. you cant choose which item u want to redeem & use when you open yours boxes. So, the next week, u can buy 10 new boxes. Happy?