1 to 2 hours. By checking the official website of Naixue's tea, the information shows that Naixue's tea comes with an external insulation bag that can be kept warm for 1 to 2 hours, and in order to ensure the taste of the drink, the user needs to drink it within 2 hours. Naixue's tea, founded in 2015, headquartered in Shenzhen, Guangdong Province, under the Shenzhen Pindao Restaurant Management Co.