I make them every once in a while. I have never frozen them, cause they don't last that long around here.
They are made with powdered sugar, butter, milk and vanilla and peanut butter. I no longer make the mashed potato version.
I would probably wrap them in Saran Wrap and store airtight in the fridge. they should keep well refrigerated.
To keep them for more than a week or two, I think freezing would be okay. My DH would eat them frozen.