Old product key is not being recognised - how to switch back to old version?

Hi, I purchased the Parallels Desktop 9 for Mac back in 2013 and have been using it ever since. When I upgraded my operating system to macOS Monterey version 12.1 yesterday, I reinstalled the Parallels Desktop software which happen to be the latest version. However, after I put in my product key for the old version, I got an error message saying that "This key cannot be used to activate Parallels Desktop". Could you advise what I need to do to start using the software again? How to switch back to my old version if needed?
Thank you.

 

Hello, Please refer to this KB article: https://kb.parallels.com/114381 version 9 is not compatible with the latest macOS. You need to purchase the upgrade license to run the latest version. Thanks, Parallels Team.