Okay, so I've made these cards to be rentals and it's working. But the problem is, when i compound the card and decard it from a card remover npc, the expiration date seems to be gone. I just wanna confirm if the card will still disappear or not.
That may be because card remover (at least, the one from Malangdo Island) deletes the equipment and then creates new items. That means that previous card was deleted from players inventory and was created a new one. That is the reason you have your card without rental.
Before the deletion, npc should check if attached card has rental state. I don't figure a way to do that check, but maybe with getinventorylist() command, but it would be something weird thing.