Every patient's journey is different. The short answer is no; you don't have to wear a retainer forever. Your orthodontist will discuss with you what options are better to prevent relapse after you stop wearing your Invisalign aligners. You may need fixed retainers, or you can use removable ones at night. You may need to use retainers only for four months or a full year, but it all depends on your specific journey towards a healthy smile.