Adobe Reader: remember password for a PDF file

"I found a solution (at least for my Mac). I've dropped the Adobe Reader and switched to Skim, a very good free, open source PDF reader, which allows saving passwords.

For an alternative solution, see this answer here on Superuser: Removing the password from a PDF file."

"Two workarounds:

put the passwords into a text file, displayed out of the way on the screen and cut and paste as required. As well as a simple text tool, any software that can provide this functionality could be used, e.g. a clipboard manager (like Glipper under Gnome) or a keyboard macro. Alternatively use a keyboard shortcut to deliver the password when required.
where possible, get PDFs from sources that do not require a password to open them for reading. Lobby other suppliers to change their policy. For example, just two from the many suppliers that do not password protect PDFs for reading:

a. Safari Books Online provide PDFs that have every page marked with the Safari username but not password locked for reading;

b. Packt Publishing changed their policy and now provide PDFs that do not need a password to read. Indeed, if you bought password protected PDFs from them in the past you can download a copy of the unlocked version for free. Again, the files have pages marked with customer details.

Commercial providers can support business cases that do not require a password for reading files. PDFs that do not require a password to open for reading simplify access, allow file contents to be searched and allow file browsers to display the front-cover icon."

"not a solution to store passwords in Adobe Reader, but a work around to remove the restrictions altogether:

PDF Unlocker is a simple and useful application that can remove all kinds of restrictions on PDF files. It works by removing passwords that restrict access in two areas. One is for passwords that restrict some functions such as printing copying and pasting. The second is any password that might prevent you from accessing or opening a PDF file.

PDF Unlocker is freeware (Windows)."