When you talk to the NPC who sells tickets from Orbis to Ellinia, you're not asked (with Yes or No buttons) if you want to buy the ticket. It's bought automatically. When you talk to the NPC wich warps you there, the tickets aren't used (they do not disappear from the inventory) You can use them as many times as you wish I didn't test that to the other worlds, but I could assume it happens the same.
