Stromboli should ideally be baked right before eating, simply to avoid the crust possibly getting soggy. However, if you need to bake them ahead of time, be sure to refrigerate them promptly, and use within a couple of days or freeze them for up to 3 months. I always heat up leftover stromboli in the oven, again to get rid of any accumulated moisture in the crust.
You are required to store it in turned off oven for a period of 2-3 hours depending on the temperature inside your home/oven. To freeze and eat later you need to wrap in plastic wrap and then wrap in foil or place in ziploc freezer bag. Read more from simplesavingsavvy.net/stromboli/.