(1) If you don't have jars on hand, transfer butter to a sheet of parchment paper, wax paper, or plastic wrap, placing on edge closest to you. Fold paper over and roll into a cylinder, twisting the ends; wrap airtight in foil. Chill until solid. Then, when you're ready to use your butter, you can just slice off little round pats of it at a time.
(2) Butter will keep refrigerated for up to 2 weeks or frozen for up to 3 months.