Disposable cameras come with a “use by” date which is basically the expiry date. You can still use them after that, but the camera would not produce as good images as expected. The colour of the image would degrade, and hence, they will lack contrast. Hence, it is better to buy a new one whenever needed. They have straightforward functions and fewer features than their reusable counterparts. Plus, they are cheap, and you have a wide range of options to choose from.