Only for a year, though
Customers only receive "a universal, lifetime right to watch a movie in any format they want" if they are smart enough to choose the correct everlasting format and download it somewhere safe in the first year - the streaming and downloading is only guaranteed for 12 months, after which time you might have to pay again. Snippets from the details as below:
"Streaming of a given title from the selling UltraViolet retailer more than a year after its purchase, or at any time via streaming services other than the selling UltraViolet retailer, may incur fees (...) with the consumer having the option to accept the fees or not use that streaming service."
"Members will be able to download at least three of these files from the selling retailer, at no extra charge above the original content purchase price for a period of one year after the purchase."