App store demands credit card information now, so i can't get updates anymore, why is that?

I bought an iPad from Apple using my credit card, the App Store on my phone seems to have noticed the purchase and is demanding I give it my credit card info too so I can continue making easy purchases there too, problem is that I don't want to make purchases from App Store yet, but now I can't get updates for the apps that I am using. How can I get updates without giving up my credit card?