Relate detail to user without user login

HI, I am building an APP so that a customer can place an order, for the only time, it does not require a user because it will not be habitual, but if I need to identify it, to improve the interface I need the customer enter in the list of products, I have an action button that when he press it adds one more product than that selected to the cart (the cart is a detail order table, saves data such as date, code, quantity, etc., once I finish choosing all the products I ask him to enter all the information send it (contact number, adress, name).
BAsically that, but the problem I have is that if I identify it by mail I cannot make a public APP, and I must pay a license of 5 dollars for each user who enters once, what I want is for me to relate all that I chose At first with that client, I don’t see that there is a session field, that it has the user’s IP or something similar. The usermail that I could use does not let me do this type of public APP.
One condition is that two different users may be selecting products at the same time and you should be able to identify them separately.
Someone could help me how to solve it so that first I choose all the products, then I enter my data and in the table orders detail I save the ID of the user.
If there was someone who could also explain it to me in Spanish, even better
Thanks a lot