for lifeOnce you purchase a course, you'll have access for life, provided that your account is in good standing and Udemy continues to have a license to that course.
You pay a one-time fee for any course and, unlike Pluralsight or Lynda LinkedIn Learning that charge a monthly subscription, your Udemy course will be yours forever.
Since its inception, Udemy has been notorious for running promotions with large discounts on their courses. In fact, it is not uncommon for them to promote courses at 80% or even 90% off to their database of customers. In doing so, they've basically trained their customers to never pay full price for a course.
Udemy course: by purchasing a Udemy marketplace course, you obtain lifetime access to that course alone after enrolling in it. When subscribed to Personal Plan, you will have unlimited access to the subscription's content as long as you are paying for a monthly subscription.