I purchased pages, but I can't print because my iWork trial is expired?

I'm using Pages 09 which I purchased through the App Store on my Macbook. I'm trying to print my document, but I'm told I can't because my iWork 09 trial is expired and I need to enter a purchased code. I can't find the code for my Pages purchase, and the App Store shows Pages already installed on my computer; aside from deleting Pages (and losing my work?) and reinstalling it to try to print... what do I do?