If you have lost your original serial number, there are official ways to retrieve it: ACDSee Pro 8 Review: Searching for Alternatives
A quick exposure adjustment tool powered by ACDSee’s patented LCE (Lighting and Contrast Enhancement) technology. License Key Acdsee Pro 8
Paste the unlock code back into the program and click Verify to complete the process. Where to Find Your License Key If you have lost your original serial number,
Input your unique serial number. If using offline activation, you will receive a "Request Code" which must be entered into the ACDSee website on a connected device to generate an "Application Unlock Code". License Key Acdsee Pro 8