Key problem

[blackadder]

2003 boxster s

I had to replace the battery in my key. Now it won't open the doors, trunk/boot or bonnet.
When it was working, the red light in the key would flash very quickly:
**************

now it is not working, the red light still flashes, but very slowly:
* * * * *

Does the key need to be re-configured to the car after putting in a new battery? Seems odd if it does, but it is Porsche. I mean, they charge extra for steering wheel shift paddles in a prestige sports car