"Can't unlock because unknown product serial number is not compatible with this version of AfterShot Pro." is caused by the having an the older version of AfterShot Pro 18.104.22.168 installed. You need to install Corel AfterShot Pro Update 22.214.171.124.
To resolve this:
1. Open AfterShot Pro and update AfterShot Pro by going to Help>Check for Updates. (If you get a window to unlock, just click "Cancel" to close the window.)
2. Download and Install the latest patch.
3. Unlock AfterShot Pro again by going to Help>Unlock AfterShot Pro
4. If you are getting an Invalid Serial number, please manually type the serial number and use all capital letters. The dashes are already typed in so make sure that you are typing the characters in the correct set. You can put your name or email address on the User Name or License Name.
You can also manually download the latest patch by click on this link.