The battery should last for about a year, sometimes longer.
The life span of the battery is, however, less dependent on usage than one might think. The reason for this is that the scale's front button has a touch sensor which always is active — this is what allows you to power up the scale so fast.
The downside of this functionality is that the touch sensor constantly consumes battery power. Because of this, the life span of the battery will be somewhat similar if you use your scale weekly as it will be if you only use it a few times per year.
If your battery has run out before one year's time, please contact Drop Support and let us know and we'll send you a new battery right away.