Does milk tea need to be refrigerated?

Short answer: No.

It really depends on how the milk in the milk tea was pasteurized. Grade A pasteurization of milk in the United States can last several days if it hasn't been opened. Milk pasteurized in other areas may be done differently, such as ultrapasteurization, which extends the shelf like even longer. But generally speaking, milk tea sold in bottles and sealed should last without refrigeration for several days. It has to because the bottles stand the chance of not being refrigerated during shipping. However, once the seal has been broken, then it needs refrigeration.