thanks for fast reply;)
I mean normal account. Customers can personalization products in my shop. They are able to create projects and save it. Project data is saved to datebase. Id_guest is in project data (I take it from Tools::getRealUID()), beacaus I have to join project and customer:) Today I noticed the problem, during testing shop (it doesn't work yet), when I was changing data in my account I lost all my projects. Id_guest was changed and I can't see my projects. So, I have to know where and when does presta change id_guest for customer. Where is it in code? When I find it, I will fix it:)