Purchasing digital videos on Amazon allows for permanent ownership of content within your digital library, separate from titles "Included with Prime". Unlike rentals, which expire after a set period, purchased titles are available for unlimited viewing as long as you have an Amazon account.
Watch, rent, or buy movies online - Prime Video - Amazon.com amazon videos to buy
: Typically gives you 30 days to start watching and 48 hours to finish once playback begins. Purchasing digital videos on Amazon allows for permanent
: Permanent access added to your "My Stuff" or "Purchases & Rentals" section. which expire after a set period