One charge of your IMR 18650 battery can last anywhere between a couple of hours or even a couple of days, depending on your use and the type of tank and coil you're using.
For example, a high resistance coil being used at low wattages (such as the Geni AeroTank), will use very little power on each inhale meaning that your battery will last much longer. However, a sub-ohm tank (such as the Arymi Gille tank) requires much higher wattages and so the battery will last around a few hours to a day.
Speaking generally, we'd expect the 18650 batteries to have a lifespan of around four months and the SERIES-B Tilt itself to last around 12 months. Both items are under guarantee for this amount of time so if either malfunction within the guarantee period, please do get in touch.