I would like to build a mechanism to free my in-app purchases for some of my VIP users devices. My idea is I pre-save the UDID of the user devices in my backend server. When the app starts, it will call my server and get the list of udid and check if the device is in VIP list. if yes, directly show full features without any button to ask for in-app purchase.
However, UDID cannot be used anymore. What should I do in this case? I dont want to ask user to enter some codes. because it would disturb my user interface.
new updates of the question:
The purpose is that , I got a list of people that they will review my apps , but i dont want to have any pop up to ask for promo code or any specific UI for these people. So my idea is I ask them to give me their UDID (or whatever number that they can identify themselves for their phone), and I save them in my backend. When they download the app, the app call the backend and compare their identifier number/UDID, see if they are my VIP, and give them full features automatically without asking promo code and any UI specific for these user.
I would like to identify the user only. Do you guys have any solutions? thanks