Parallels requires 2nd Windows serial key?

I have bootcamp installed on my computer and it runs just fine. However, I downloaded Parallels today in hopes that I would be able to run it fine, then Windows asks that I type in an activation key. However, seeing that I already activated Windows many months ago on my machine I would hardly think this would be necessary and I've already used the serial key for bootcamp. Have I done something wrong here? Thanks!

 

Hello!

You have to activate Windows one more time for use with Parallels,

Best regards,
John