If you are using the lube after a long time, you necessarily have to do a small test to ascertain whether it is still safe to use. Just take the lube in your hands and see whether you feel the same when you used it last time.
Check if there is any change in the colour?
See whether it has become thinner or too translucent? Check whether it smells any different?
If you find anything strange with any of the above mentioned, then it is better to discard the lube and buy a fresh one. The feeling of safety is much more valuable than the cost of the lube.
Don't just look at the expiry date and start using it if it is well within the expiry date. Remember, lube is a chemical that can change with changing times and in the environment where it is kept. So, do a physical check before blindly using it based on the expiry date.