The Short Version: 3 days officially. It’s 0 days if you let it overheat. It’s …? days if you keep it good and cold.
The Long Version: We recommend consuming your plantmilk within three days of opening… but there’s a slightly more nuanced take on that. If you let your plantmilk get too warm for too long, it’s going to go off. That’s without even opening it! But, if you keep it nice and cool from doorstep/shopfloor to fridge, it can last a fair bit longer.