It can be a little difficult to answer questions such as these as all it takes is one device to change the answer. However, speaking from a general sense, more times than not a soil pH meter is going to automatically reset as soon as you remove the probe from the soil. Yet, if it is a digital version and it is programmed to leave the reading on the screen for a certain amount of time, this may not end up being the case.
For the most part, assume the former; especially when you are talking about pH meters need to be directly inserted into the soil. Logically, it makes sense as when you pull the probe out of the soil, it technically is now reading the pH level of the air. Sure, it would be nice if the reading would stay for several seconds but just bank on it resetting.