JimThePCGuyFormerly known as schja01.Premium,MVM
Morton Grove, IL
The monthly recurring charge is per device. I never saw a discount for multiple devices since I became a customer back in March. There are frequent hardware price discounts. Expecially in the second half of the month but those don't depend on multiple devices per account.
So I think my answer to you is the price remains the same per device and per plan even with multiple devices.