yup - lady Cindy is spot on - i would definitely fifo it to the front of the line... my current vapeocalypse stash is 500ml in argon purged glass with a one way septum valve on it - and i have close to 2000ml on deck that i am working through... when i open a bottle, i break it down into 50 or 100ml glass bottles for storage, so that i am accessing smaller amountsI would still use it, but I would use it NOW, instead of saving it for later.Even if it's a little discolored. That just means it's oxidized a bit, and if anything, it might not be the whole 100mg. May be more like 80-90mg. Now if weird green things are floating on the top, different story.
Also, is it in glass? Then no problem. If it were in plastic, you'd have to look up the decomposition rate of the plastic.