Unopened, all makeup (except mascara and nail polish), has a shelf life of about 3 years; unopened mascara has a shelf life of 1 year, and unopened nail polish is good for 2 years. When opened, look for changing signs, drying up, clumping and color changes are a visual sign (for liquid and cream beauty products), that the makeup has run its course. It's harder to tell with powders, try to keep all the makeup brushes clean (wash them with mild soap and dry flat every 2 weeks.