and other articles show an 8GB memory limit for this OS.

What I might try is:
1. Clone the HDD because.
2. Now on the Clone try to get the W10 Upgrade. How?

That so you can:

A. Hope the upgrade avoids the 99 buck OS charge.
B. does not show a Windows 10 Basic.
C. Windows 7's time is ending. I will not open a conversation about wanting to stay on W7.