Concealer expiration date

I bought a concealer on an overseas trip a while ago, and when I saw how well it covered my skin, I truly experienced a whole new world.

But even so, I don't do makeup that involves using concealer every time, so

My face is covered in blemishes, so unless I use it liberally, I won't be able to finish it before the expiration date. Is it okay to use it in this case? I just feel a bit uneasy about it. But the amount isn't decreasing at all. It feels like I'd have to apply it all over my face for a whole month to get rid of it.