> "Operating system - Windows 7 Professional 64 (available through downgrade rights from Windows 10 Pro)"
Microsoft will stop supporting Windows 7 after January 2020 -- less than 3 years from now.
By then, you will have to run Windows 10 to keep your computer's security updated.
So, you need a "long-term-solution" for your requirements.
Note that Windows 10 Pro has the capability of creating an emulated Windows 7 environment, so that your application software will run in a "virtual" Windows 7 environment.
Have you contacted the vendor of the software, for their recommendations on how to run their software under Windows 10?
After all, Windows 10 was released in July 2015 -- a long time ago.
The vendor has had 20 months to fix their software to work under Windows 10.
For Windows 10, the traditional 10-year support lifecycle continues, with a five-year mainstream support phase that began on July 29, 2015, and a second five-year extended support phase that begins in 2020 and extends until October 2025.
Mainstream support means that any problem reported to Microsoft will be investigated and fixed.
Extended supports means that any security-related problem will be investigated and fixed.