Is a pre-paid annual subscription to a delivery service permissible, which allows an unlimited number of deliveries?

This annual subscription is permissible, and the lack of knowledge regarding the extent of benefit derived from it does not cause any harm, as it involves a slight gharar (uncertainty), and the fee is determined in a way that accommodates this slight gharar. Muslims have unanimously agreed on the permissibility of matters involving slight gharar, such as selling a padded cloak, renting a house for a month, entering a public bath for a fee, and drinking from a water-skin for compensation. This is because necessity dictates engaging in such gharar, and it cannot be avoided except with difficulty, and it is an insignificant gharar.