Food-date language is not identical in every country. Advice from another market may use familiar words in a different regulatory context, which makes broad statements about dates unhelpful.
In the UK, a use-by date relates to safety and should be followed even when food looks or smells normal; best-before generally concerns quality. Other countries use different conventions. Check your local food authority's guidance and the actual package.
Opening can also change the storage period. A date for an unopened product does not cancel an instruction to refrigerate and use within a shorter time after opening. Write the opening date on foods you tend to forget. Smell is useful for noticing spoilage, but it cannot establish that all harmful microorganisms are absent.
Further reading: UK Government: best-before and use-by dates.