There's a fair amount of information about this if you use the search.
PEAs are generally stable chemicals, and N-Benzyl PEAs are not much different. The 'safe' conditions for any compound will generally be somewhere cool/cold but not below freezing (if the temp fluctuates above and below the freezing point water may get into baggies etc through small openings made by the freeze-thaw cycle), dry, dark, and generally as airtight as possible.
These conditions are much more important for some compounds than others, like 4-subbed tryptamines. NBOMes don't need this level of protection though, they're hardy compounds. If you want to store it double-bagged in a plastic baggie in a desk drawer that would be more than adequate.
Try the search engine, like I said these sorts of questions pop up a lot.