After you purchase Lil' K.T., you'll receive a code that can then be redeemed on any European or Russian World of Warcraft license via Battle.net Account Management.  European and Russian licenses include realms serving players in the EU and the Russian Federation. 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 World of Warcraft in-game pet code applies to all present and future characters on a single World of Warcraft license.  If you wish to purchase the pet for multiple different World of Warcraft licenses merged with the same Battle.net account, you will need to buy a separate pet for each World of Warcraft license individually. 
The full Pet Store FAQ can be found here: http://eu.blizzard.com/support/article.xml?locale=en_GB&tag=PETSTORE