[cantrevealname]

No. I personally have a video message that is almost 3 years old that I've tried to delete multiple times over the years and it still shows up if I do a fresh install of Skype on a new computer.

Very old voice messages are also accessible even if "deleted".

Text chats do seem to disappear, but at this point I don't believe anything Skype says. I figure they keep the chats forever as well.

[yeukhon]

Chats are definitely saved, but files aren't. You can't retrieve files after certain amount of time. I can also retrieve conversation from 3+ years ago. I don't remember if there is an option to forget conversation history though.

[wjagodfrey]

In all fairness, that's not say they're not being moved to deep physical storage. That's a practice in many organisations dealing with mass data.