Sorry for the stupid question:
I was running a shiny server open source on a linux server (Ubuntu 16.04.xxx).
Today, I just installed the trial shiny server PRO on top of it.
Everything seems to work, but how can I be sure my app is using the PRO server and not the open source one? (I suppose the server has been upgraded and the open source version does not exist anymore, but I would like to be sure)