Users may be prompted to verify their credentials each time they open a Microsoft Office or Adobe Acrobat file. This repeated request for credentials is a result of Microsoft /Adobe design and is not related to the Nomadesk service.
Additional information can be found in this article on the Microsoft Knowledge Base.
What you could do as a possible workaround is to open a file, log in, and then leave that file open. If you then open a new file with the same extention it shouldn't request a new log in.