How to Block Multiple Logins /Sign Up?

So, I have an App where the user needs to sign up to access the app. I'm planning to run an offer where user can order that item only once in a day. But I have the doubt that he may change login Id (if have multiple emails) and can place the order with Different ID's.

I'm thinking of registering the device with an email id:

Pros: - Not able to login with a different email Id.

Cons: - Not able to use the app on a differnt device ( if changed) as it may give an error email Id already registered with another device.Which leads to deregister from the previous device (Chances device may not be available).Or raise a ticket which is time-consuming. this may lead to customer loss.

Have also, read about IP tracking, Phone number, and Credit card details but not satisfied with the answers (somebody already raised for same). So what will be a good method to avoid multiple logins/sign up from the same device?