I am new user in HPLC Agilent,thank you.
As far as I know, there is no "Best before" date. If you store it in the appropriate solvents and you keep it in good condition, I do think it can still work, but the performance might not be exactly what it was. But you would have to test it out.
What I usually suggest is to make a chromatogram of what you expect with the whole method attached. And if you want to use it again in a year or 2, go back to those condition and that exact method and try it out and look at the chromatogram now vs before. That will tell you how good the column is still.
Obviously 2 years is a very long time to have a column sitting on a shelf, so I would not be too surprise if the performance drops a little bit at least.
If you want the least performance drop, I would suggest giving it a good cleaning. Then putting it in appropriate solvents. Store it in a zone to avoid vibration, extreme temperature or moistures.
https://www.agilent.com/cs/library/troubleshootingguide/Public/HPLC%20Column%20Troubleshooting_012210_Rita%20Steed.pdf P.7 gives you an idea on how to clean your column