I don't think it's possible to recover the serial number for Greyhound Wizard because there is no primary website to obtain the necessary steps to do so. I've searched the web up and down but did't find anything which could also mean that Greyhound Wizard is a discontinued application.
The only thing you can do right now is to install the application and then access its About section, maybe there are some contact options there. You shouldn't need any serial number. If it's possible, run it in demo mode or trial.