Jag slår upp saken!
Sony Knowledge Base: Sonic Foundry software will not register online
Download the Sony Media Software Online Registration Repair Tool from HERE. Be sure to download the application to a place you can easily return to. You should also create a backup of the application for future use.
Close any Sonic Foundry software that may be open on your computer.
Double-left-click the downloaded application detailed in section one above. This will install the Sony Media Software Online Registration Repair Tool.
The Sony Media Software Online Registration Repair Tool will first scan your system to identify legacy Sonic Foundry software. It will then repair the links for online product activation.
Launch the Sonic Foundry software that is giving you troubles and register online. Product activation should work as expected.
Om jag förstår saken rätt söker programmet själv först, och i ditt fall hittade den mp3-pluggen. Men sen ska du kunna köra igång Sound Forge manuellt, med Repair Tool igång, och kunna aktivera programmet igen.