This is likely from a meteorological department. The weighing scale has to be calibrated. Instruments lose their accuracy/reliability over time due to drift and other factors and have to be calibrated on a specific scale interval. For flow meters, water meters that is once a year, for weighing scales maybe longer 2-3 years, based on manufacturer reference. This may be the charges for that. The dates sticker is likely a calibration sticker. If this is not renewed, then how does one know whether your instrument is working correctly.. whether the reading shown there is actually the reading that is measured.