Need help with software licensing!!!!!

This is my first job as a Network Admin. One of my dauting task is software licensing. I need to make sure that we are up to date and compliant. The problem is that prior to me, this issue was always pushed back and no one did the software licensing. I have no experience in software licensing. I know there are volume license, open license, etc. Also, the company has no software to manage inventory or software. I will probably have to do this via spreadsheet. Can anyone tell me the best route to take?