Today is the last day. Bethesda is hiking the price of the Season Pass from $30 to $50 to account for its “increased value” from tomorrow on, so if you really, really want it, grab it today. However, I wouldn’t suggest doing so. Right now, there are two micro-DLCs on offer, as well as a larger area called Far Harbor. There’s “more on the way,” but we have no idea what that actually entails. In fact, all three announced add-ons are still sight unseen, so even $30 is a bit much on good faith.
I think it’s fine to choose however you want to spend your money, but as we know from history, there may only be $15 worth of good add-ons anyway. Especially if the price hits $50.
Fallout 4 [Steam]