If you are premium, they stated that you can already have five pets, but they haven't set it up to show up on the userlookup yet, that's why there wasn't a big announcement.
---------- Post added at 11:42 PM ---------- Previous post was at 11:39 PM ----------
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My 5th Neopet is not on my user lookup because new Premium isn't launched yet. In our development environment, he's totally there with the rest of my Neopets hanging out. All your Neopets will show up. You don't choose four out of the five.