Are you sure it was LauncherPro Plus you paid for?
LauncherPro Plus is basically an authorisation you pay for to unlock the "plus" features of LP. It's done through LP rather than through the market, because many regions still don't have paid apps on the market.
If you search for "LauncherPro Plus" in the market it returns "android agenda widget" as the top result, but I've no idea why - as far as I can tell that widget has nothing to do with LauncherPro. I guess that's what you've installed, and I'm sorry, but I think the blame here lies with the market search throwing up something unrelated rather than the LauncherPro developers.
Install the free LauncherPro, and if you like it, or want access to the extras, then use the link within the app to go pro. And don't blame the LP devs for the market search's error.
Note: I have no connection with the LP devs, other than using their app.