My liquid tube doesn't have a date. How long is it good for? I bought it January 12th 2014. Stupid of me to have let it hang but I had to. I brew in Baja and **** happens.
It should have a best by date on it which is supposed to be 4 months after it's made. So if you bought it Jan 12 then you will have passed the best by date. It may still be usable, definitely make a starter if you're going to use it.
I've herd 6 months after date of packaging. But even after that it will be fine just a low cell count. If you make a starter you will be fine. I have used white labs vials that were over a year old (with a starter) and been fine.