At this point, the palette has sentimental value and since I've only hit pan on three out of the 16 shades, getting rid of it feels like a waste.
No matter how expensive, rare, or beloved, every product will eventually go off. The stability of an emulsion isn't infinite, and it breaks down over time.
When to throw away liquid makeup
When to throw away lipsticks
There's good news: Old powder eyeshadows, blushers, bronzers, and highlighters might just be okay to use.