YoGen Recorder has been discontinued and is so old that it's almost impossible to find any details about it on the Internet. You can, of course, try to activate the 3/5 version of the application using the key you have, but since you most likely made the purchase over seven years ago, the chances for it to work are very slim.
The only advice that I can give you is to try contacting the application's developers using this email address wechat@yogen.com and see if they can help you out.