What is a convenient engine for paid services?

Question

CMS

The task is as follows - a person submits an application for the performance of certain digital services, after which the service itself forms a price for him according to his application, performs the work himself and after - notes the status of the application - completed, the customer can then pay online.
It is also important that all these applications be non-public, through a personal account.

Answer 1

Billmanager

Answer 2

whmcs