No, you are not permitted to keep the blankets provided on United Airlines flights. Regardless of whether you are flying in Economy, Premium Plus, or the high-end Polaris Business Class (which features luxury bedding from Saks Fifth Avenue), the blankets are considered the property of the airline. They are collected by the flight attendants at the end of the journey, sent to a professional facility to be laundered and sanitized, and then repackaged in plastic for the next passenger. Taking a blanket is technically considered theft of airline property. However, you are allowed to keep the items found in your Amenity Kit, such as the eye mask, earplugs, socks, and skincare products. If you truly love the quality of the Saks Fifth Avenue blankets used in Polaris, United occasionally sells them—along with their specialized pillows—through their official online "United Shop" or through their loyalty program rewards catalog, allowing you to own the "cabin experience" legally.