Laptops and laptop batteries have become very popular for most households. The common mistake most customers make is to leave the laptop plugged in to the power. Unlike a desktop PC laptop was made to be used on its battery. If the laptop is plugged in all the time, the battery never gets a chance to discharge.
The laptop should be unplugged at least once a week or so to use it on its battery, through a full discharge. Then the laptop can get plugged in to recharge.
This helps the battery by having the electrons go through a state of change. Instead of the constant state of charge, from leaving a plugged in all the time. Laptop batteries can be around $100 to replace. Good battery maintenance can get batteries to last approximately three years, before having to be replaced. So use the laptop as it was intended and the battery should give you many years of use.