IQFeed doesn't limit the number of apps connecting to it simultaneously. There are some quirks though in that it doesn't keep track of the multiple apps, so if one app asks to remove a symbol, the other app will lose it also. Also, some of the 3rd party apps automatically try to launch IQFeed, even if it is already running. Thus, it will pop the error that IQconnect is already running, and the app won't load.
Our next version of IQFeed will resolve these issue by doing the checks for the 3rd party app.
In the original post you mentioned you wanted to connect on multiple machines. This won't be supported as the exchanges don't allow it. The data cannot be re-distributed outside of the original diplay device.
Hope this answers your question.
Jay