A "Use By Date" is put on products that must be used or disposed of before the date supplied as these foods will deteriorate and could become dangerous to consume.
A "Best Before Date" is put on products to indicate that the product is literally best before the date supplied but can still be used after that date.
When used with culture products the "Best Before Date" is applied by the manufacturers who must allow a certain leeway for the time the products are in transit etc. and are not being stored as proscribed. Given that both our suppliers and ourselves take great care to ensure these products are stored correctly prior to shipment we are more than confident, and experience has shown, that these products will be able to be used successfully well past the dates on the packaging.