Can I Use the Demo Keys for Development or Testing?
No, the demo keys are useful for interactive online demos only and for trying out PubNub with the PubNub Dev Console. And the demo key are throttled to prevent abuse so any app using the demo keys may not behave as you would desire.
For development and testing of your app, please register for a free account and use those keys. Note that using the demo keys implies that anyone subscribing to the same channel you are publishing on will receive those messages.