I actually have been taken up my mixing hobby again recently, after 7 years of only mixing my tobacco liquids. My flavour stash contains about 200+ flavours. I started trying them out again as i was afraid that after so many years they would not be good anymore.
I started out with the flavours i bought back in 2012. To my surprise they still taste very good, maybe a little different from back then (i cannot remember exactly how they tasted). So far, I tried about 20 flavours (tobacco, fruit, drink, candy, nut, bakery) and no flavour has turned bad. Very happy 'cause it was quite an investment...
The flavours are all stored in boxes, in a dark cabinet at room temperature, where the temperature fluctuate between 20-32 degrees Celcius.