We are a software company developing a system using Google Maps for our customer internal use (commercial, with GPS device). I know that our customer need to have Google Maps premier license.
My question is: Does my company need to pay Google any license fee for development purposes?
(IANAL and I don't speak for Google)
I would definitely check with Google and/or get your own lawyer's opinion, but the bolded section below would make me think that you would not need a premier license for the development phase.
9.1 Free, Public Accessibility to Your Maps API Implementation. Your Maps API Implementation must be generally accessible to users without charge. You may require users to log in to your Maps API Implementation if you do not require users to pay a fee. Unless you have entered into a separate written agreement with Google or obtained Google's written permission, your Maps API Implementation must not:
(a) require a fee-based subscription or other fee-based restricted access; or (b) operate only behind a firewall or only on an internal network (except during the development and testing phase).