A prom is meant to be a one-of-a-kind moment, but if you are going to the expense of purchasing a fancy dress, you do not want it to go to waste. That means you may want to think about other possible uses.
Alter It
Wear your prom dress in different contexts by having it professionally altered. Change the length and straps or sleeves for a new look. You could also dye it a different colour.
Wear It for Halloween
It may not be the first thing you think of as a Halloween costume, but a prom dress with some strategic rips or fake blood can be a highly effective yet relatively simple choice that echoes some famous depiction.
Preserve It
After all that time spent finding the perfect dress from somewhere like https://www.ohelloclothing.com/collections/debs-prom-dresses, you may not want to damage it, even artistically, or let anyone else wear it. You can preserve it with careful washing and then store it away from any damp or sunlight. You will be able to reminisce, or even wear it again, many years later.
Donate It
Prom dresses can be expensive, and not everyone can afford one, meaning some people simply do not go to what is meant to be a crowning moment of their school life. Many organisations take donated clothes. If you would prefer to keep it close, you could donate it to younger family members instead.
Sell It
One way to make back some money whilst helping others is to sell it, whether to someone you know or through an online marketplace.
Swap It
Maybe you have multiple proms or other events to attend, so you need multiple prom dresses. Swap with a friend of a similar size so you can change your look with no extra expense whilst also helping someone else with their outfit.
There are many things you can do with your prom dress, whether keeping it in altered form for yourself or allowing someone else to make use of it. You can be quite creative in your choices.