Create a form to protect another and only give access when some datas are availables in database

I want to protect a testing form from being taken many time, as this content is sold. I need to send the url of this form to a user who order from hikashop the access to form named DiagP. I don’t want the perso has the possibility to copy the diagp's link and come back to do it many other time. So I created this formA to protect the second one formB= DiagP 1- I want the user a. fill in all the form, and add the code generated. If you can have more complexe code generated, i would appreciate. b. When a user submit, we should check the DB of the form A, to see if he has already submitted previously, if not, then, we will check that all his data are already in hikashop table, that means he has ordered, then, we will store all his data in formA. We will also store a hidden value, which show that he has already take this form c. After saving datas in DB of the formA and checking that he really paid, if he pays (data found in hikashop (Name, Surname, Email, and order number), we will redirect him to the form B =DiagP d. I don’t want the diagP url appears directly, as user can copy it and come back, so if there is a way to modify this url, or to pass some variable of the form into this url, i will prefer that e. I also want a peace of code (that can be add in custom code) to prevent from taking diagP many times. f. When the user has already take the diagP, a message should warm him saying that you have already take this diagP, with the code : xxxx showing the code he had enter while accessing the diagP through the formA. I started a form, but it always say that, i have already take the diagP. All features used should be native chronoforms features (DB read, to access hikashop datas, DBsave, redirect...)