According to this article, Microsoft has announced that it will indeed start charging Windows 7 customers a monthly fee from January 14th 2020, if they want to keep their computers safe.
Microsoft has always described Windows 10 “as a service” and leaks have already revealed new monthly charges are coming. Of course, for Windows 7 owners this was never something they expected to pay. But times change…
Source: Forbes: Microsoft ‘Confirms’ Windows 7 New Monthly Charge