12d27f1 created the issue

Hello,

I noticed that the single text "Not a valid registration key" remained untranslated over years in Cyberduck.
(in Cyberduck menu from the menubar).

It appears that in tansifex, the translation vocabulary used a couple of times is "donation key".
Inded "Not a valid donation key" is available and translated.

Would it be a misuse of the right string?