From the Super Mario Wiki
KerokeroCola (sometimes spelled Kerokero Cola) is one of the most valuable (and most expensive) items found in Super Mario RPG: Legend of the Seven Stars. KerokeroCola has the ability to recover the HP and FP of everyone in Mario's party. It can be purchased at Tadpole Pond after acquiring the Soprano Card or in Marrymore via room service in the honeymoon suite. KerokeroCola comes in a green cup with a picture of a green anchor or in a frog-shaped bottle.