Pecans have natural oils that make them flavorful. To prevent the pecans from drying out and becoming rancid, you should keep unshelled or shelled pecans refrigerated. They maintain their quality refrigerated in airtight containers for up to 9 months. For long-term storage, keep them in an airtight container in the freezer. They can keep that way for two years or more. Desirable is the best variety for storage long term.
The Texas Pecan Growers Association has several recipes using pecans you can try.