The life span of a hearing aid is usually about 5-8 years, depending on the individual's use, maintenance and so on. It also depends on the user's hearing condition. So I can't give you an exact number of years of use. I've seen hearing aids used for more than 10 years, and I've also seen users change their hearing aids after 2 years of use. Individuals are different.
Manufacturer's warranty is usually about 2-3 years, but some manufacturers and distributors will have some activities to extend the warranty period, which is not regular activities, and less. You can pay more attention to it.
Of course, if you are hard of hearing, you need to get a hearing aid as soon as possible, and don't wait for the manufacturer's and dealer's activities just because of the warranty period. The sooner you get a hearing aid, the better it will be for the patient.