Yes – you must always disclose with either a label or a placard the ingredients and allergens in your products- even if you are giving away samples or offering a client a tasting, such as for wedding cakes.
These labels and placards don’t need to be elaborate, but they do need to be present. This is as much for your own protection as that of the consumer. You don’t want anyone alleging that you’ve hidden allergens or falsely accusing you of substituting ingredients.