Adding more license keys to a running license server is easy, just drop the new license file in the same folder as your Reprise License Manager (the RLM Directory), then Reread/Restart the servers. Not sure where this folder is? It's the one that usually contains the following files.
rlm
rlmutil
lightmap.set
You can put multiple license files in this directory. RLM will read all files with a .lic file extension in this directory.
...