Cooked vegetables will keep for up to 4 days in the refrigerator before they go bad.
The cooked vegetables then start growing bacteria, mold etc on the vegetables even when refrigerated.
To see whether or not your cooked vegetables have gone bad take a look at them and check for any signs of mold or change in the color of the vegetables.
If you notice the mold or any other change in color then throw the cooked vegetables out.
Smell the cooked vegetables as well and if the vegetables have a bad smell to them then they are bad and should be thrown out.
If you want to keep your cooked vegetables longer than 4 days you can place the cooked vegetables in a freezer safe container or Ziploc bag and freeze the cooked vegetables.
The cooked vegetables when frozen will keep for up to a year but it's best to eat them within 6 months.