EC (electric conductivity) meters and pH meters require regular cleaning and care in order to work properly. Since these are precise measurement tools, they tend to be very sensitive. Therefore it is necessary to store them in a special medium, known as storage fluid - e.g. a KCL solution. It is also a good idea to use a dedicated cleaning fluid, such as HCL solution, that ensure reliable readings in both EC and pH meters.
Another important thing in professional pH and EC meters is calibration. These are done either manually, or (more often, and depending on the type of the device) by a calibrating fluid. Most popular solutions are pH 4 and pH 7 for pH meters, and 1413 us/cm (1.4) for EC meters. These are solutions with guaranteed, known pH / electrical conductivity, allowing the device to be calibrated.
Since both EC and pH meters have their limited longevity, you may have to replace the electrode after 1-2 years depending on the quality, frequency of use and manner of care. These could be bought separately for most kind of devices.