This depends significantly on how the battery is maintained. Under healthy conditions, the battery is rated for 800 cycles. This could last 5 years or longer depending on use and storage/care of your battery. Additionally, regarding charging batteries, they can be charged on or off the bike and has its own LCD gauge for charge levels.
Keep your battery charge level between 30-80% as much as possible. This will significantly increase the lifetime use of your battery cells.
Don’t store your battery plugged into the charger. Charging should be monitored, and batteries should not be left plugged into a charger.