I don't have a card, but as I said in my "No time for shame or blame " post, I'm not afraid to let it be known. The other day I was checking out at Fleet Farm. I took my bag of purchases and put it in my cart while I waited for my credit card to process. After I signed, and got my receipt, I started looking for my bag again, forgot that I had put it in the cart. The cashier told me it was in my cart, I apologized, and she said "no problem, I do it to." I added, "I've got an excuse, I got hit in the head."
I don't hide it. I realize that the tiniest of distractions make me lose track of what I am doing. I make jokes about it, because it can be really funny if you are able to laugh at yourself. Most of my friends know I'm not as "in the present" as I used to be. They are very helpful and understanding, and are used to my humor.
It may be helpful for me to get the card though because, even though I know all the local Sheriff's Department,(you don't provide 16.5 years of IT support without making friends) I do travel outside the county on a regular basis and at times find it hard to concentrate an all the details of driving(urban speed limits can be hard because you also need to watch traffic, signs etc.) I don't make a habit of breaking laws, but I'm not as able to process as many thoughts or as much concurrent input as I used to.