Where are WinRAR's keys?

Hi all, I have recently bought and installed WinRAR on my computer. However, I previously had used a 40-day trial before. Now, whenever I install the trial program, it says the trial has expired. I find that kinda annoying, even though I have the paid version. Installing the paid version on top only does not rid that message (it's on the top bar, not the window itself). Where can I find the 40-day trial (reg?) key and delete it? Thanks for the help!