The PR is also confusing - it could have been more clear. I could be wrong, but it does look like the past sales going back to 2007 is included in the total - that's the way that I'm reading it. And it makes sense assuming the 17.5 cents per phone based on Lenovo's / Motorola's annual shipments that I posted in my prior post.
I think that interest should be added - it almost always is:
<<The Court ruled that Lenovo should pay a total of $138.7 million for a license to InterDigital’s portfolio of 3G, 4G and 5G patents, and should pay in full for past sales dating back to 2007. The Court will decide in due course whether additional interest is due on the past payments.>>