Hi,

I don't know what you mean exactly... I try to explain how I think you mean it .

You MUST use the Serial (included in WoW box) when you want to play (the first time). You can't create/activate an account without this Serial. It's NOT possible just to use a Prepaid-Card Serial to create/activate an account.

Once you've created an account (with the Serial included in the WoW box) you can extend your playtime with Prepaid-Card's (or via Creditcard). In Germany (I don't know if this is also possible in other countries) we can also extend our playtime via our phonebill.

If your playtime expire, you'll see a message when you try to login to the game. If this message shows up, just go to the website where you created your account (when you install the game, it'll guide you how to create an account) and extend/charge your account.

It's harder to read as to do ... you'll see it's easy .