Place the dates in the bowl of a food processor fitted with an S blade. Process until the dates are broken down and form a sticky ball.
To the food processor, add in the nut butter, oats, flax seeds, and salt. Process again until the batter becomes crumbly, which may take up to 2 minutes. Stop and scrape down the processor, if needed.
Press the batter between your fingers to make sure it will easily stick together. If the batter is too moist, add another 1-2 tablespoons of oats for flax seeds. If the batter is too dry, add another 1-2 tablespoons of nut butter, and blend again.
Use a tablespoon to scoop the dough and then roll it between your hands to form balls. Place them on a lined plate or baking sheet, and then transfer the pan to the fridge to help them firm up, about an hour. (Though you can eat them right away if you want to.)
For best shelf life, store the balls in an airtight container in the fridge for up to a week.