Minecraft Problem

[Nilnoc]

A friend and I bought Minecraft a few weeks ago.
He created the account and used his parent's credit card.
But when I log onto the account online, it still gives me the option of buying the game. He is able to play it on the computer he bought it from, but I can not play the game in browser or the downloaded client.

My friend has emailed the company at least twice, but the problem has not been resolved.

Any help is appreciated.
Thanks.

[Vonn]

You're not trying to play the same account at the same time, are you?

[Nilnoc]

No, we're not.

I tried it with him right next to me, and it didn't work.