Chocolate – Can one use chocolate fèves/callets/nibs for tempering

Low quality chocolate chips often have additives in them that help them keep shape and shelf life, that's why they're not recommended. Callebaut callets are pure 100% chocolate according to Callebaut. I'd use them anywhere for bar or chips with great results. They might not come out of the oven looking exactly like a traditional chocolate chip cookie (for example) but they should taste fantastic!

If we're referring to plain chocolate bars, I say go for it. Plain chocolate (unsweetened, milk, or dark) lasts, if unopened, for years. The most that will happen is that the outside turns whitish in color, but this does not affect taste or quality. If there is any sort of filling, though, I, personally, would not eat it more than a month or two past the expiration date.