First, I should check how EA handles game keys these days compared to 2009. EA uses Origin now, which is their game platform. So maybe they sell the game through the Origin Store, which would issue a CD key when you purchase it. But wait, if it's an older game, might it be available on other platforms too? For instance, maybe Amazon, Steam, or other digital stores have the game with a key.

Additionally, some people might have the game on physical media but the disk is damaged. In that case, the CD key is needed to activate if they want to redownload. They need to contact EA support to retrieve the key or get help activating it.

Another point: The game might be available as a "Classic" title on platforms like EA Play (which is similar to Xbox Game Pass for EA games). So perhaps a subscription could work. Let me check EA Play. Yes, EA Play includes a library of games, which might include Half-Blood Prince if it's part of their catalog. If that's the case, then instead of a CD key, you just install it from the Origin app once subscribed.