Beatmatching
When you have beatmatched two beats, and changes from track A to track B, how do you do to take the beat B back to normal speed? because it sound weird if you use the pitch changer. And of course everyone needs to do that
You simply move the pitch fader back to 0 but most of the times you don’t want to reset it back to it’s original speed. Are you using master tempo (keylock) on the decks? that prevents the key from changing while you slow/speed a track.
Thank you so much! 
i have wondered what the key lock button was for. Are the professionals nearly always using that?
master tempo like padi said
I barely use master tempo/keylock. It makes some tracks sound inappropriate, I only use it for vocals and MAJOR tempo changes, like 10%.
But you must if you are going to make a transition?
Usually you would stick to mixing between songs that are already at a similar speed.
I just keep the same tempo, so no pitch movements while the track is playing. So no, I don’t have to! Or am I not getting the question…