Hey Vexor17
The rules of proper long term storage don't discriminate, no matter what the substance in question is. Obviously some compounds will be more resistant to degradation than others but you always want a form of storage that'll reduce or eliminate the amount of thermal and UV radiation the compound receives in addition to atmospheric exposure.
Now me personally, I just use an air tight amber glass vial wrapped in aluminum foil and store it in the freezer, but since you've already mentioned that isn't an option I'd look for the next best (or coolest) place I could possibly store it, which of coarse only you could know in your personal residence. Another thing I may or may not have heard correctly is some people storing their N,N-DMT in non-polar solvents in which they precipitate the alkaloid out when they wanna use it. I'm just gonna assume at the top of my head that this will protect the compound from oxidation in a similar manner to how reactive metals are often stored in oil. I just wanna end off by saying this kinda topic has already been discussed in good detail, so just look around the forum a little more and you should find what you're looking for.
Thank you very much. That was very helpful!