The website listed as being the developer's one appears to be discontinued. But here is a thing you can do: upgrade to Windows 10 and then check if the software is working. Eventually, apply a compatibility tweak by right-clicking on the executable file. If it gives you errors, then go back through Start > Settings > Update and Recovery > Recovery > Go back.
Windows keeps a Windows.OLD folder on the system drive, which is the previous OS and restores it when the function is triggered from the Recovery.