How to make the payment through ROBOKASSA on the landing page?

Good afternoon. There is a landing page in php, it sells the processed photos. The bottom line is this, the user uploads a picture, processes the filters, and then after the payment available to him this photo in full size. I can't understand how after payment provide the user with exactly the photo that he uploaded. Please tell me how to link it.
On the website there is no registration and things like that...
July 2nd 19 at 14:07
4 answers
July 2nd 19 at 14:09
Create an order with a unique number.
Order fields: id pictures, price, soap user.
Send it to RK to pay.
When RK will tell you that the payment has occurred (this may be after the user has fulfilled all his actions and was returned to your website) - send him by email a link to download the finished pictures. All.

Well, if anything, the cookies remember this user and show him the same link on the website when he will be there again.

But to build a cooperation pattern on the assumption that he paid for, went back to the website and that's it, a picture would be a big mistake. It is possible that the site of his return will not yet know he paid anything or not.
July 2nd 19 at 14:11
In case of successful payment, ROBOKASSA makes a request to ResultURL, respectively, to this address must be the delivery of the goods (photos)
July 2nd 19 at 14:13
Without registration payment? Seriously? And what You will do if the payment is not going to take place? Will force the user to close the window 3 days?
And failed to connect?
At least the user should be a unique link with which to pick up the order, but then the security issue arises. Anyone can pick up. So that check probably need.
At least we must take the email to which to send results or a link to it.
But I still do not understand why not to do the registration.
Offer on lindose check to do? If payment is not work, it just will not give a successful result, i.e. will not spread to the product page. - Caroline.Herzog commented on July 2nd 19 at 14:16
: What's lendin or not. There is payment, there must be registration - Henderson_Beat commented on July 2nd 19 at 14:19
July 2nd 19 at 14:15
I agree with the previous speakers. It is necessary to something to bind. If you don't want the check, or soap, or generate a link and in big letters to alert the visitor that the link he needs to somehow save.

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