I have experienced a similar problem as I'm getting an error with my activation key. I have replaced the hard drive in my Mac and when I tried to use Parallels 11 it required activation. I got the following error: "Unable to confirm the product licence. You have reached the maximum number of activations available for your activation key (http://www.parallels.com/eula). Please purchase a new product licence." But it's the same Mac that I'm trying to use it on, just with a new hard drive configuration. I have signed out of Parallels on the old drive.
Cheers Brian
Last edited: Apr 14, 2016