It depends on how long you plan to store it. Its "best used by" is for the flavoring and it's about a year. Most say more and I agree. So no need really unless your storing for a long time like me. It is a fact that fridge keeps your juice fresher so I keep all my mixing juices (I have lots and they will last another year at least) in the fridge and my made up mixes (that I know will be gone in a month) on top of the microwave ready for use. I have a cart of juice almost 8months old and has been left out and it still tastes fine and has plenty of nic still (I make high nic mixes so I can tell in two puffs if it's strong or not). Hope that helps ya
I'd say if you plan on holding on to it for more than a year than yes you should keep it refrigerated. Any less than that and it's not needed.