Siehe https://support.steampowered.com/kb_article.php?ref=2347-QDFN-4366
If you purchased software through Steam with a credit card, please provide the following:
* The Card Type (Visa, MasterCard, Discover, American Express)
* The Cardholder’s Full Name
* The Credit Card Expiration Date
* The last four digits of the credit card number - Do not provide the full credit card number
