As the software is of the nature that it will require updates indefinitely (as OS updates come and go), and given the fact that the license is specifically for commercial use, I decided to go with a subscription model instead of a one-time payment model to ensure its long-term sustainability.
I am lucky that this specific software is very "sticky" and already has a die-hard fan base. It also helps that people in the Windows ecosystem are used to paying for commercial use software licenses.
This month to date I have made $800 on license sales. It will be interesting to see how the license sales continue to progress (or don't?) throughout the rest of the year.