Best Storage:
Fridge
Store whole unwashed green beans in an airtight container in your fruit & veg crisper. Only wash them as you use them.
Freezer?
Yes
Chop the ends off and Blanch for 2-3 minutes. Cool in ice water. Dry and freeze in airtight container or re-useable zip lock bags - remove as much air as possible to prevent freezer burn. They generally last up to 3 months without loosing much nutrition. Add to cooking from frozen
Use it up!
Use them up in stirfries, salads, and casseroles, or as a healthy snack by themselves.