It is advised that you toss out your make up after about 12 months I think. I wouldn't wait too much longer than that. By the time it changes texture, consistency, colour and smell, it is probably way too late. I wouldn't be continuing to put it on my skin/ lips. Chemicals can change over time, so who knows what it would do to our delicate skin.
I wore some liquid makeup from an old little tube, years ago. We gone to visit them, via a 3 hours train trip. By the time we arrived I had a very bad rash on my face! They took me to their Dr, & he suggested I use a moisturiser for sensitive skin. I throw out the tube of makeup when we arrived home, & never got around to opening the $16 container of the cream, which is still sitting on a shelve in the en-suite!