I was wondering.. how is the data stored in the Power FC?

If the Power FC is completely disconnected from the car, are the setting wiped out the same way they would be with a stock ECU?

What I mean by this is if I take a Power FC that has already been tuned by someone else.. will all settings revert to the default settings when I put it in my car?.. thus making a re-tune necessary?

Also, if that isnt the case, how do you make a Power FC revert to the stock ECU settings?

Any info would be appreciated