In the last month I rec'd a letter from Amex stating that we are no longer allowed to keep the Amex CIDs either. However, I have a problem - what do you do with it if you don't keep it? Obviously you can't just remember them all, what are you supposed to do, write it on a piece of paper, keep it in the safe, and then shred it three weeks later when you ship? I'd be very interested to know what other DBA users do.
Anyways, we use the Company Name field to store the CID. Please don't tell anyone