Pending it's kept in a stable environment (~65 F, low moisture content, out of direct light) there's only a handful of drugs that will actually lose potency anytime soon.
So they're not going to go bad, or become toxic it anyway. If anything, just less potent. But seeing as SARMS are not regulated by the FDA I don't see what would constitute an expiration date, and furthermore SARMS haven't been made by supplement companies for all that long...
...what's the expiration date?