It depends if they are filled or not. When plain (unfilled with a cream), they can be kept at room temperature in an air-tight container for up to 3 days. They could technically be kept for a little bit longer than this but I find them to loose their shape and become soggy after that time. Once they are filled with a cream - and if they are not going to be served straight away - Choux à la Crème need to be kept refrigerated and will keep well in the fridge for up to a day.