What can I put on our
license='(c) My Company',
'License :: Other/Proprietary License',
Technically, there is no fundamental difference between licencing open-source and proprietary software.
In both cases you should include a
LICENCE file specifying what can and cannot be done with your software (see this related SO question). It is also advised to add a short copyright / licence header to every code file in your project (in case they get copied outside of the original package folder).
It is possible to mention the licence type in
setup.py, however that field is mainly used to display the licence for Python packages uploaded to PyPi. Since your code is not open-source (and won't be uploaded to PyPi), this is not very relevant in your case.