Until a few years ago, it was common for Android devices to stop receiving features after about 1 year and then stop receiving security updates after 2 years. Unless you’re getting security updates another way, which may not work correctly and may even require you to build Android yourself, you should not use the device for anything important after that point. The batteries would be next to useless by that time. Now it seems more common to get three years, which isn’t great either. iPhones last longer, but they come with all the iPhone problems.