I think it depends also on how the car is used and stored.
My old Mitsubishi Mirage had it's original OEM battery from the factory (Built in October 2013) and I just sold it in the summer, just shy under being 9 years old, never had any issues with it, though I was expecting to, so I had a jumper pack in the car just in case!
The car was also parked indoors in a heated garage for almost all of its life, so it had a pretty easy go of it.
You can also get a garage to test your battery (or try buying or borrowing a battery tester) to see if it's holding a charge correctly, though if you're worried it might just be easier to replace it as they're not that expensive in the grand scheme of things car wise!
Temperature extremes are hard on the battery, too hot or too cold and it will reduce the battery life faster, leaving the car sit unused for very long periods of time is also hard on the battery.