Changing file type without purchasing more software

I was sent a photo in a .pi file and I am looking to see if I can edit it without purchasing more software. I need to get it into a format where I can use it for posting, editing, and other files. I was going to ask the sender to change the format, but I'd prefer if I can find a resolution on my own. Is the only way to do this to purchase more software? Adobe is asking me to buy something else but I am wondering if there is a way around it? Thanks.
