This PC runs with Windows 7.
I'm afraid we cannot guarantee any of our software will continue to work on it, since Windows 7 went entirely out of support this January and, when an OS is unsupported for users, it become unsupported for developers too, because we use Microsoft VC++ to compile the software, and when we update our tools ( Visual Studio ), we get newer versions of system libraries that our software inherits, which are normally distributed by Microsoft through regular Windows Updates.
But since Windows 7 is not being updated anymore, it's likely the reason the software doesn't run, is that you are missing some components that our software requires ( likely new VC++ redistributables ), and you might not even be able to install them, since they might even stopped to support Windows 7 themselves. While we haven't done anything to INTENTIONALLY block Windows 7, we have no chance to verify the latest version of our software still wok with it, that's why we now indicate Windows 8.1 as the minimum supported OS, even if we strongly suggest to use Windows 10.
The problem is, even if you had an old installer, due to Esellerate closing down last year, we had to switch to a different ecommerce provider ( Soraco QLM ) which can still activate old keys from Esellerate ( we uploaded them all on the new server ), but it requires the current version of the software, and with the old version, one that might still run on Windows 7, you won't be able to reactivate, because that version connected to Esellerate servers, which are no more.
So, I'm afraid you don't have many choice other than update to Windows 10, if you want to continue to use our products.