Just started using LaTeX so pardon my ignorance here. I was wondering whether style files created for example by Cambridge University Press are free to be used for commercial purposes (a book, respectively) or whether you need a special permission of the publisher? Any help is very much appreciated, preferable with link to the source that provides this information :-)
The classes of the Cambridge University Press include these lines at the beginning of the file:
So I'm afraid you can't use them for other purposes, except with special permission of the copyright holder.
A lot of packages have the licence statement:
the LPPL can be read here or simply run
Special packages, which are not on CTAN may have other licence statements with some restrictions. However, I cannot see a problem when using packages from publishers for writing a manuscript.