If you are planning to eat your pie today you can go ahead and keep it out of the fridge in a cool, dry place. If you are going to eat it tomorrow or a few days from now, just put it in the fridge. Fruit pies will last about a week and custard based pies will last 4-5 Days.
If you decide to serve your pie warm put it in the oven at 300 for 10 minutes or so.
You can find detailed instructions for freezing our pies here: https://pielady.com/how-to-freeze-a-pie/