Just like with any other electronic that you will own, fire alarms and smoke alarms do not last forever. When you first purchase your alarm, there should be information printed on the package or on the directions that mention how long the alarm is good for. This is especially important for the kinds of alarms that have the built in batteries as once the batteries are done, so is the alarm and you have to buy another.
If you moved in somewhere that already has some fire and smoke alarms, or you simply do not know where you last put the directions, you should still be able to get the information you need. Take the fire or smoke alarm off of the wall and look on the back. There should be a date printed somewhere on the back. This date indicates how long the alarm is good for. After that date, you will have to purchase a new alarm to replace it.
Most of the time, fire and smoke alarms will last a good five to seven years. It really does depend on the company that produced them though. However, while this is a general rule of thumb, it is not something that is set in stone so it is very important to make sure that you are investigating to find out just how much time the fire or smoke alarm really will last.
When you are staying on top of such things, you will be able to remain safe from the dangers of fire. Always check your fire or smoke alarm batteries and replace those and the alarm itself as needed.