Move Parallels 8 license key to another Mac

Dear all,
I tried to move my license key from Parallels 8 from my older MacBook Pro to MacBook Air and wanted to deactivate the old installation, but there is no way how to do it...
How can I deactivate the license key of Parallels 8 on my old MacBook and migrate it to the other one?
I am still using Parallels 8 for compatibility reasons and want my license to be migrated. When trying to activate Parallels via the license key on the other MacBook, Parallels always tells me that the maximum amount of activations for my Parallels 8 liencese key has been reached... I am not able to find any option on how to deactivate the license key on the old Mac... Trying it via Terminal command also does not work...
Can you please help me?
Best regards,
Markus

 

Hello,
We've reset your Parallels Desktop 8 license key, please check the issue.

 

Dear Maria,
thanks a lot! It did work now...
Best regards,
Markus