The latest version of Bicom Systems PBXware Sound Converter uses an API key to register with PBXware. When prompted during the installation procedure, open up your PBXware GUI and click on 'Site Settings->API key'.

Now you need to generate a key by clicking on 'Generate API key'. Copy and paste it into the PBXware Sound Converter. After you start it, it will automatically register itself and you will be able to use it.