MariposaC

I will be going on my first cruise on the Allure of the Seas for an 8 night Southern Caribbean cruise and there is a total of 4 days at sea. I saw a posts a few weeks ago where somebody posted their cruise compass and they had the option to buy a single day drink package for sea days. I wanted to know if this is a common option on sea days. I understand it will be more expensive per day than if I buy it ahead of time but I really only want the option for a few sea days. Does anyone know if they offer this on all sea days?