E-liquid, if stored in a cool, dark and dry place, especially ones without nicotine, can have the original taste for as long as 2+ years. However, we suggest you use the e-liquid and cartridges within 12 months after the manufacturing date, especially if Nicotine is present. Remember that the longer you store the liquid for, the thicker and darker the liquid will become and the more the flavor and nicotine strength will degrade, however it will not go bad.
In the case of the Cartomizer models, we suggest you consume the cartridges within 1 week of unsealing (removing the leaf seal). However, if not un-sealed, they usually maintain the original taste for 2-years from date of manufacturing for nicotine-free units. If nicotine is present, we suggest using it within 1-year for original taste and strength.
All e-liquid should be stored at room temperature, ~21°C (70°F). This will ensure that it keeps its flavor, strength (if nicotine is present) and stays fresh.
Depending on the conditions, specifically heat, light and air, e-liquid may change in color due to oxidation or due to the nicotine in the liquid. It certainly doesn’t make it go bad, but it changes the taste and if left for a long time, may make the taste and strength get weaker over time. The process happens slowly over time, and is much slower if stored in sealed and dark conditions. Presence of oxygen, heat and light accelerates the process. Nicotine-free e-liquid stays fresh for longer, usually 12-18 months, if kept in ideal conditions.