Let's start with best by dates. They are an indication of quality, not safety (i.e. expiry or use before dates*). Typically conservative, these are an indication of how long before it begins to dry out. Drying being the primary quality concern for snus.
*FoodSciencebabe does a really good job explaining if you want to more on this.
Let me reiterate, there are virtually no food safety concerns with snus. It's pasteurized and treated with more salt(s) than bacon. No bacteria is growing here unless you introduce some super strain yourself.
So, why do we freeze or refrigerate? Quality (read: moisture loss). The cooler it's kept, the slower the moisture evaporates off.
Safe to assume your snus will be at optimal quality up to (and often beyond) the best by date when refrigerated... and it'll keep damn near indefinitely frozen.
Whether I freeze or refrigerate, I bag my snus before storing. I'll buy the nicest gallon freezer bags I can find. Why? Odor migration. Garlic, seafood (or any other potent smell) can make for a nasty snus experience.
I keep a can of lös and a can of portions on me at all times. It stays at room temp until I kill the can (2-3 days for the lös and up to 10 for the portions). Never had any quality issues at this rate of consumption.
Beyond that... I try not to "shock" my open cans with extreme temperature fluctuations. i.e. leaving it in a hot car, taking a can from my pocket and putting it in the fridge. Luckily, I'm a white collar powder puff that spends 99.8% of my life at a comfortable 69⁰ F... so it's rarely a concern for the snus in my man purse.
Only other consideration is shipping. In the dog days of summer if my order gets stuck in a dreaded customs loop in hot trucks/warehouses... it might lose a few weeks of "best by" to the heat. Even then, it's barely noticable. US General is no longer even refrigerated. So, all this thought and effort might be for naught.
That said, this has been my practice for nearly 20 years... so even if it's baseless, it's habit (ritual?) I'm likely to maintain.
Here's what Swedish Match has to say...
https://www.swedishmatch.ch/en/what-is-snus/qa/
Hope you find this info helpful, and... Happy Snusing!
