Use this leftover up properly

Half a tub of something and three days left on it.

Tell me first whether this is still good, given how long it has been in the fridge and how it was stored. If it should go in the bin, say so and stop there. Otherwise give me three uses ranked by how completely they use it up, with the extra ingredients and the time for each.

Leftover, quantity, and how it has been stored:

Cooking from what you have. Dinner out of the fridge as it stands, leftovers to use up, and swaps for the thing you are missing.