Metatrader EA restriction

I am in the process of having a EA developed and if the real money tests are as good as the demo tests, I hope to offer access to this EA through a monthly membership. I need to restrict access to this EA to the following. I would like to allow access to the EA for demo trading only, no real trades with this access. The demo access allows potential customers to see the trades materialize without the ability to trade a live account unless they pay for access. I also need to allow access to the EA for live trading to those who have paid their monthly fee. No payment and their access is cut off.