I have a large bottle of deep rose gel food coloring that I purchased several years ago. Does food coloring have and expiration date or would it be ok to use?

i find that after a year or so, they tend to dry out, but if it's still liquid I use it. 

AI'm pretty sure it's good forever. Even if it dries out, you can revive it with a bit of glycerin.

http://thedecoratedcookie.com/2010/05/all-about-food-coloring/

Thank you.