Every probe comes with a small case that the tip of the probe sits in. This small case must always contain storage solution to keep the semi-permeable membrane in the tip of the electrode moist during storage. You run the risk of damaging the probe if the tip dries out, and this damage could result in having to replace the entire meter. Short term effects of a dried out probe are incorrect pH measurements because the meter cannot get an accurate reading through the dried tip. It happens more frequently than you may think, and it is always more advantageous to have extra solution not only for this reason, but in case you accidentally knock the tips case over and spill the solution everywhere…it happens.
Get the solution, store the cleaned meter tip in the solution at all times, and enjoy having a healthy and functioning pH meter!