Fresh lemons will keep for a couple of months by being completely submerged in a ceramic crock of cold water. Simply place the lemons in a clean ceramic crock and cover with very cold water.
Place a small plate or water filled plastic bag on top of the lemons to keep them submerged. Store the crock in a cool location like an unheated basement or root cellar. Change the water every week or so and you’ll have a supply of fresh juicy lemons whenever you want them.