Yeah, I would like to know this too.
I was thinking of wishing for a renewel of my Premium Sub BUT I also want to b sure that the store credit is included. Or else I rather ask for money and buy it myself and get it as a gift coupon. Last year I won a community competition and won a Gold membership but there was no store credit along with that. Was that because either the code was won/earned or bought during a sale?
I just want to be sure before I ask. And where can I find this info? I found it nowhere in the Faq.