S.T.A.R.S. office on the second floor can be opened by that key. The locked door initially reads next message: "It's locked. You'll need the S.T.A.R.S. Key to unlock it." The plate near the locked door reads "S.T.A.R.S. Office". This key can be discarded after opening the S.T.A.R.S. Office, using the system message, that appears on unlocking.