Originally Posted by CloudCoder

Perhaps there's a time constraint? I originally (back in May) ordered 2 cards for me and 2 for spouse, total of four cards. Today it let me order another 4 cards (2 for me and 2 for spouse). I tried to order more but could not.

Conclusion: there's definitely a limit of two cards per account. Apparently, after sufficient times passes, they allow another two cards per account.