Just to correct everyone in this thread...
The dealer uses ODIS to program the keys.
The key must be a dealer-authorized key that is pre-coded to the car before programming.
That is the only thing that the dealer will do.
For aftermarket, there are several options. Even if you have the active/proximity key, there are options. I have a C7 S6, repaired it from a salvage title with only one key. I wanted another key, didn't want to pay a bunch of money for it.
The steps for using a junkyard/ebay key are:
-Get the right key fob. There are many versions of these keys that look very similar. Some are active/prox keys, some are not. Some use a different NXP chip than others but look identical. Really all that matters is that you select the correct type (prox or not prox) and have the same NXP chip.
-Get a replacement blade for the key. The aftermarket blade won't fit quite right on the fob even if it is the right one and this takes a tiny bit of dremeling of 2 nubs on the fob or the blade (dealer's choice) and cut the blade.
-Get someone to "virginize" the key fob (or do it yourself). If you are into learning electronics, the resources are out there, there are quite a few dumps on transpondery.
-Use one of the aftermarket tools that will add an (unauthorized key) to the car. I used Autel. Pre-code the (virginized and unauthorized) key using the "Make Dealer Key" function, and then program it to the car. Keep in mind that with these tools you must have at least one working key. You used to be able to do it via OBD even if you had no keys for the car, but VAG shut the servers down (used for calculations of sync data) about 2 years ago and that is that. Now if you have lost all keys the only way to do it outside of the dealer is to jailbreak the (encrypted) BCM to read the data from there, but doing this may potentially result in the dealer refusing to service any BCM related complaints in the future, so that is "at your own risk".
Edit to answer one of OP's original questions: The badging on the key is irrelevant. The ebay key I used is an unbadged key, probably from a C7 A6 that had the active/prox option.
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