Motor Oil in a car or vehicle typically lasts for 3,000 to 5,000 miles before it goes black and dirty and needs changed.
I change my oil every 3,000 miles which is about every 6 months of driving for me.
I work from home so don't drive that often but when I worked away from home I would rack up 1000 miles in one month or 3000 miles in 3 months so my oil needed changed more often.
As long as you're changing your oil every 3,000 miles to 5,000 miles your car should be fine.
Also always change the oil filter every time you change the oil as the oil filter gets dirty as well and they are cheap and easy to replace.
Motor Oil that has never been opened can last for years because it's actually old to begin with but it has been refined and formulated for the engines.