I am constantly amazed at the relationship the average slashdotter has with management.
it looks something like this:
slashdotter : always has the right answer / opinion
management : to stupid to see / understand / do what I said.
obviously this is NOT reality.
In my opinion the typical reason for this sort of relationship is poor communication from the technical side.
I've worked with HUNDREDS of management teams, and yes there are certainly inept or incompetent ones.
But to the original poster, as an IT pro, it is your job to couch technical needs/issues in terms a businessman can appreciate.
So please disregard what so many people here are telling you about not being able to get management to do anything here...
here is what you need to do:
Document ALL available licenses, regardless of how old (as in old unused versions - sometimes will show them what they thought they bought is no longer used). talk to accounting, and have them find ALL purchase records, even if there are NO physical media, licenses, etc. You need to have every scrap of info, so you can then ask "what am I missing? when your boss says they bought it already.
Document ALL installed software (ocsinventory-ng is a great tool for this)
Suggest options, with costs associated. (as indicated by previous posters, 7zip, and OO.O, are options, or they can pay the licenses OR compare that to what a BSA audit could cost, and how easily it could come)
Once you have clarified it all, my guess is that a reasonable decision will be made. It might not happen immediately, but you should be able to spec a project to phase the changes in.
I once had a client who was similarly refusing to pay for software, despite my warnings "this could be a problem" and "you aren't licensed for this". I continued to install unlicensed versions, largely due to inexperience, and "the customer is always right" attitude.
They got a threatening letter from the BSA, and quickly turned to me and said "we'll you are taking care of this for us, so how could we be out of compliance". I basically converted them to the FOSS shown in this thread, and made them buy the rest. MAde sure all was kosher, and then said see ya.
lessons learned. I simply am unwilling to be out of compliance now, for my personal sanity. because once you wave multiple $250k fines in someones face, they will look for a scape goat somewhere... you need to be ahead of the game on this. Had I done my job, and PROPERLY instructed them on the risks of their decisions, it would never have gone down like it did.
These folks were douchey, but I believe that had I expressed the needs correctly the situation would never have occurred, because at the end of the day they are businesspeople, and money talks.