Typically, a well-made, fresh laptop battery will last for 2-4 years. This amounts to about 1,000 charge cycles, give or take. After this period, it is best to get replaced with a new one.
Obviously, several factors determine how every individual battery is going to perform. Not every battery is built the same way nor will it have the same durability.
How long it lasts primarily depends on your capacity to take care of it properly.