DIY Nut Butter Recipes and Tutorial Including Homemade Nutella from Tasty Yummies. This is the best and most detailed tutorial I have ever seen for making nut butters (including Nutella). I also just saw the worst DIY nut butters on another site that will make people cry if they try it.
This tutorial includes soaking and then dehydrating the nuts before blending them. These should last for several weeks in a covered glass jar in the fridge, but you can freeze them up to 4 months. There are recipes and tutorials for: