Hi Jared,
I honestly could be wrong here, but the way I understood it was that license files have a hard-coded date associated with them. Otherwise, you could just keep installing it and it would apply a new time frame.
One way you could test this so you don't mess up your environments is to create a sandbox BP environment (could just be a local DB and no app server), install the previous license, then install the new license, and see what happens. Unless the client licenses work differently from the Partner licenses (for training use), the date of the license is whatever BP sets it to when they deliver it to you.
I don't handle purchasing licenses so take what I say with a grain of salt (I'm mostly replying because no one else was), and my only experience with installing them is using the Partner training ones.
Respectfully,
Dave
Dave Morris, 3Ci at Southern Company