In some cases. It is called secondary prevention. For example, If you have already suffered from a heart attack, you have to continue anti-lipid drugs rest of your life (in most instance).  In some cases, like familial lipid disorder or history of premature coronary disease (heart disease due to excess lipid/cholesterol) in family as well as you have some risk factors in you (obesity, hypertension, DM etc) you might need to continue the drug for uncertain period.