Honestly, like a lot of non-food products, even after expiration, there's a good chance it'll still be usable. It's not like it's going to rot. Maybe it'll degrade a little (and even then, not sure... I have make-up removing water that expired months ago and I never saw a difference), but apart from, say, lipstick that would dry and just refuse to be applied, it would be surprising if you had to throw it away. I'm not sure, but maybe you can put the spare one in the fridge. Stuff tends to last longer in there.
PS: In the future, I think it would be good if you tried to make your topic titles more significant. For example, "makeup question" is very vague, but "How long does make-up last?" tells us what the topic is about right away.
