When kept in a cold, dark environment and kept in a tightly-sealed jar or container, mace spice may last longer than most other spices. The taste of the blades and ground mace should last for a year or more, although after six to eight months, the power may diminish. Mace blades that slightly exude oil when squeezed with a fingernail even after they have dried are still regarded as fresh. To guarantee that mace is consistently aromatic and tasty, don't refrigerate it and think about purchasing a modest quantity at a time.