Sour cream will last between 1 to 2 hour out of the refrigerator depending on the room temperature.
If the temperature in the room is 90 F or above then the sour cream can start going bad within an hour of being out of the refrigerator and if the room is cooler than 90 F then the sour cream will last up to 2 hours out of the refrigerator.
When you're done using the sour cream you should immediately refrigerate the leftover sour cream to prevent bacteria from growing in the sour cream.
If you keep the sour cream refrigerated which you should do then the sealed container of sour cream should last 2 to 4 weeks past the use by or sell by date.
You can freeze the sour cream if you want to keep it longer than a few weeks to a month but I would not recommend freezing the sour cream because if you do it won't have as good of taste or texture once it thaws out.
I would recommend eating the sour cream within a few weeks to a month of buying the sour cream and if you open the container of sour cream it should last a week or two weeks before going bad.
If you notice the sour cream has a bad smell to it or the sour cream has mold on it then throw out the sour cream and don't risk getting sick.
Always refrigerate the sour cream within a few hours of using it to keep it fresh and prevent it from going bad.