Want to get a general idea how long these things can go before there is some error. A part fails or some thing not related to human error.I have about 40 flights on my P3P, no errors or crashes. But I see a time when somethign will fail.

Depends ;) Many people fly them years with no crashes, some crash all the time, some just have minor problems.. As long as you inspect it all, check the props, make sure you battery is seated well, pay attention to the warning in the app.. I would expect it to work well at least a year...... hope for more - but I assume eventually the electronics will start having issues....
Certainly interested in what others have to say.... If this was 1970, I'd expect equipment like this to work for the next 50 years ;) Good old build like US, Germany, or Japan used to do it....

To tell you the truth as I have observed it, either there will be a problem with the hardware almost right away,  which is actually pretty rare considering how many of these things are out there,  or you will not have a hardware problem until you crash.  That being said,  the odds of you having a software problem are a little higher,  but the odds of you having a user initiated problem are far and away highest of all.  No one can really claim to know all there is to know about these things,  but a whole lot more than you would believe hardly know anything at all about them.  They just open the box,  pop in the battery,  try to fly and mostly crash,  mostly not too badly,  but still.