The freeze-dried petals are absolutely beautiful the way that they are, but if you would like to further 'soften' your freeze-dried petals - to give them a bit more suppleness and pliability - you can do so by placing an open container in a steamy bathroom (say after your morning shower) for 20-30 minutes so that they soak up the gentle moisture and regain an more of an elasticity and texture similar to fresh petals.
Please note that one you have softened your rose petals in this way it's best to use them the same day or within a few days, as adding moisture back to the petals means they will not last as long as they did when they were freeze-dried. For uses such as decorating aisles, tables or using as confetti
Keeping your petals freeze-dried means that they will last for months, even years, if you keep them in the right environment (a cool, dry, dark place such as a cupboard)