What is the best practice to monetize an Creator App through the Developer platform?

What is the best practice to monetize an Creator App through the Developer platform?

We are new to the Developer platform, we have created a couple apps for clients but are still not clear on the correct process to monetize and collect using Zoho Developer.
Here are some questions we are looking to get cleared:
1) Is it necessary to add one user in the client´s account to add an external developer?
2) Is there a way to get Zoho to charge the base user fee, plus the developers margin to the client in one transcation with the client? We saw something similar with the Developer CRM option.
3) Do the basic limitations for the client´s Creator account apply? For instance, if the client has a basic subscription, is he limited to 3 apps?, etc.?
Thanks
Constantino