Pistachios are available in many different forms such as unshelled, shelled, salted, roasted, etc. It’s is always advisable to settle on raw, shelled pistachios rather than processed and salted ones as they lose large nutritious values while processing.
Also make sure not to pick the pistachios having some cracks other than the natural cleave or having rancid smell.
Stock up the shelled pistachios in a sealed, airtight container and unshelled in a cool, dry place. You can also freeze or refrigerate pistachios for almost one year.