If you incorporate these ingredients in your cooking, your left-overs will last longer:

  • honey
  • salt
  • garlic
  • sugar (only in high amounts according to feedback; small amounts shortens the life)
  • ginger
  • sage
  • rosemary
  • sage
  • mustard
  • cumin

Additionally from other articles:

  • black pepper
  • mustard seed
  • turmeric
  • cinnamon
  • cardamom
  • cloves

Acids mentioned by others:

  • vinegar
  • citric acid
  • lemon/lime juice

I just had some harissa get moldy after just a couple weeks in a jar in the fridge. I was surprised. I suppose it implies a lack of the above ingredients.