If you purchased classes previously on Craftsy.com you will continue to have lifetime access to that class! You can find all of your lifetime access classes in your regular Craftsy account Class Library or see the details of your purchase in your Craftsy.com Order History.
You can still purchase classes to own forever from Craftsy.com as well! You will only have access to stream classes on Unlimited while you have an active subscription. If you cancel your subscription, you will lose access to Unlimited content, but you will always have access to any classes you've purchased to own.