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 (we’re talking over 5°C for more than five or 10 minutes), 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.