After you purchase Soul of the Aspects, you'll receive a code that can then be redeemed on any European or Russian World of Warcraft license via Battle.net Account Management.  This pet code can be emailed to a friend as a gift, or—if you would rather redeem the pet code yourself—automatically filled in for you in Battle.net Account Management.

Once activated, this in-game pet key applies to all present and future World of Warcraft characters on a single European or Russian Battle.net account.

The full Pet Store FAQ can be found here: http://eu.blizzard.com/support/article.xml?locale=en_GB&tag=PETSTORE