Do you know how long it lasts in the Fridge? Asking as going to get supply ahead before 1 January 2021.
I think longterm storage in the fridge or freezer is pretty much unknown as most people haven't had to do it till now with new juice freely available. Anecdotally there is enough info to know that it will last longer if frozen than stored at room temperature. I've put some in airtight bottles in the freezer only recently and I think a lot of us may be in the same situation. We're trying to cover our tails in case there is an import ban. No harm in freezing some without having all the storage answers I reckon. #VapersgottaVape
Short answer from me? "I'm not sure"... There are a lot of different factors involved, so I don't think there's going to be an easy or precise response for you here I'm afraid.
I can tell you that I store my 'easy mix' bottle(s) in the fridge, and I've never had any of my base discolour significantly, or noticeably change in taste, over a 6-9+ month stretch. Talking more long term fridge storage than that however, the problem you're faced with is that most folks will use a freezer instead. Hence, the relevant data points for fridge storage might be a bit limited.
FWIW, and to the best of my understanding, nicotine deteriorates faster with exposure to light, or oxygen, and temperature/weather can play a role too. So limiting the influence of those factors is likely to improve the longevity, wherever it's stored.
You can tackle the light problem by storing in dark or opaque glass. Oxygen exposure can be mitigated by decanting into smaller bottles, and leaving less liquid exposed to the air inside. If your fridge is working as it should, you'd assume that weather wouldn't be too much of a factor, though extreme heat or power failure might be an issue worth considering too?
Other than that, I don't have much for you I'm sorry, but hopefully it helps.
* When stored in the freezer it lasts a LONG time. YEARS. Several around these parts tell of stuff stored 5 to 6 years in the freezer still as good as when put down. I've seen 4 years out of the freezer myself, and the stuff was as good as the day it was put down.
* Fridge would be better than cupboard, not as good as freezer. Obviously.
* If not stored in fridge, then general recommendation is in glass in a "cool dark dry place". Can't offer specifics, but I know I'm still occasionally vaping stuff I mixed at least three or four years ago. That juice was held in the proverbial cool (well, allowing for Perth summers) dark cupboard. In plastic. It was mixed, ready for me to vape way back then and it still vapes today as well as it did way back when mixed(*).
I'm guessing long term storage success is affected by the quality of the products being put down as well as the storage conditions. I mean, if the source liquids are already "partway done" I don't think you can expect maximum storage life from it. I'd expect that, to maximise storage life, fresh, good quality PG/VG/NIC together with best storage conditions both play a role.
* Steamers Plime, with about 50/50 PG/VG in case any one's interested.
I have held nic for up to 7 years in the freezer , and its been fine when used .. Although all mine are PG based ... VG will go off earlier and espescially if the lid has been cracked before storage .... VG can support some limited feral wildlife growth but only at room temperatures and even then its hard for a colony to get started .. if stored subzero growth is practically 0 ...
I think provided your "easymix" is kept sealed and cold and out of light as much as possible you will get years out of it
I store all my e-liquid in an airtight container in a wine cabinet.
I only recently entered into DIY e-liquid so can not comment on that BUT last week I opened a bottle of 12mg flavoured e-liquid ( a flavour I do not have very often) that is dated 26 December 2018 by the maker. It is fine.