Luckily, these inks are the longest lasting items on any desk. If kept properly, these fountain pens can last up to 6 months. It is important to note that these inks dry faster if exposed to air. So, if you are keeping it properly stored in an airtight container, the ink can last up to a year and a half more. If the pen has an additional cap (that generally lies in the bigger cap), it lasts for up to 2 years or more.  You can also extend the life of ink by storing it in dark and cooler places and airtight containers.