Hi Mithrandir77. FXCM answer is a little complicated:
a) FXCM allows multiple connections from the same IP - API and/or Trading Station.
b) Without doing anything special, FXCM allows 1 API connection and 1 Trading Station connection to the same Real account. I don't think this limit applies to Demo accounts.
c) If you need more than 1 API connection to the same Real account (e.g., multiple Zorros trading in 1 Real account), FXCM requires multiple access paperwork first.
HTH.