Because when you enter the multiplayer mode, the purchase info among with the credit card is verifyed. If there is no more credit card info, the DLC will not be available in game. I just posted this above:
"Aaaa... secure site you say? Then, why my credit card data was missing 2 days after I added it and purchased the DLC?
Yesterday when I tried to play online, an error message appears saying "Failure to load DLC proof of purchase" or something similar. So there was no LE unlocks (these are free) and no DLC maps. I entered gamesas.com/store and in the Purchase History there was the LE code and the DLC. In the Payment method - "no credit card associeted with this account". WTF... Where did my credit card data go?
After I added it again, I was able to play the DLC, and the LE bonuses appeared."
It's a crap, I know. I want to remove the credit card info too, but presently, we can't. They must modify the methode for verifying the DLC, first. Why they are verifying it: because anyone who bought the DLC can pass it to others for free. It's just a zip file.