[Paul]

From Sunset Imports (a Porsche dealer) who charges $105 to program a key:

The remote portion of the key is sold separately from the metal cut
key part. The metal cut key portion can be transferred to the new remote or
a new blank metal key can be sold and cut by your dealer or a qualified
locksmith and then snapped into place in the new remote. The bar code that
is sold with the remote is necessary for the technicians to use in order to
program the remote to the cars anti-theft and central locking control
system. If that bar code with the programming codes is lost then the remote
fob cannot be used as intended. This is why buying one off of ebay is a
waste of money. When bringing your car in to have one key programmed you
should bring all the keys that you have. The other keys might lose their
programming codes and get overwritten by the new key code. This includes the
non remote keys, as they also have a transponder that has to be programmed.
The transponders only function is to start the car. On push button remotes
they are programmed to lock and unlock the doors as well as programming the
transponder inside the remote key fob. Non remote key heads are also sold
but they don't include or need the bar code tag that new remote key heads
come with. You need to take your car to your local dealer to get the
programming done. This can't be done over the phone or by VIN#. The car,
remote, technician and special tool must all be together in order to get
this done. The car will not start unless the remote is programmed to the
vehicle. I don't have access to any of these codes.