If i start taking lopid (gemfibrozil) , will i have to stay on it forever?

No: No. It can be stopped at any time.

Not Necessarily : Lipid medications are used to treat a defined cholesterol or triglyceride disorder. If the lipid disorder is the result of another treatable medical condition (e.g., hypothyroidism, diabetes, etc.) then treatment of these conditions, as well as improvement in diet and exercise, can lessen or eliminate the need for lipid medications.