Rides after the license plate expires?

Hello, I bought a motorcycle from Private yesterday, which season registration mark 04-09 attached. Will pick it up on Friday. Can I drive to the registration office (directly) for re-registration? Stay also in the same registration area. I already got a full double card. Or do I have to get such a stupid red number for a one-time ride? On the net you will find very contradictory opinions. For quick answers I thank you.