If you’re 100% organised, there’s a chance you may not need to recover a password from a PDF file.
I’ve got a lot of PDFs scattered over my hard drive and some of those have a password attached to them.
Usually I rename them so that the file name tells me what the password is. But occasionally I don’t do that and then need to hunt through emails or MSN chats to find what the password was.
Other people I know get sent password protected PDFs at work and they either have to add to their collection of Post It notes or find somewhere else to store the password.