From experience, I have never had a problem using a coffee card on several ships until it is used up. I bought one on the Allure and used the remaining slots on the Freedom and Odyssey.  I bought a new one on the Odyssey to use on this  S2S2S I’m doing right now. Today on the Jewel, I decided to purchase four coffee cards to give as gifts to my friends who are going on a pre-Christmas cruise on the Allure.  Someone at Café Latte-tudes told me that coffee cards can only be used on the ship o