If you got the House version, like I do, decant into glass bottles and put in the freezer. If you are about to need one of the smaller bottles soon (within a month or so) it is fine to leave out, but otherwise I'd stuff them all in the freezer.
Glass is used because it's impermeable and doesn't leach (most plastics do, to some extent, particularly if it's long term, years).
Oxygen is what causes oxidation, while heat speeds things up - for long term a mostly full glass bottle (only a small bit of air in it - no harm), in a very cold dark place (a freezer) is the best.
Fill the bottles near full - neither pg nor vg expand when cold.
A lot of us add a bit of tape after the cap is on, a final seal binding the cap to the bottle.
After taking a bottle out of the freezer, give it a day to come up to room temp, then a good shake before using it.
The unbreakable note is "klutz prevention". I'm comfortable handling my single in-use bottle, and am not about to drop bricks onto the bottles in the freezer. The bottles I get from HV are pretty sturdy, I have no problem stacking a couple layers of them in plastic bins in the freezer.