License Price For Cloud

I am hesitating regarding Cloud Price in ErpNext
Let’s say, I need self services for 5 Users, and will calculate Payroll for 50 Employees, and just I need the cloud hosting, not support

Is it mandatory to pay for 55 Employees, or will pay for 5 Users

Did you already check out Frappes Cloud? It’s also by the makers of ERPnext but without support. So far I have been very content with it.
Here is the pricing structure: Frappe Cloud Pricing
(Nice addon: you are supporting the maintainers of the project and thus the project itself instead of a random hosting provider)

The pricing is based on data usage instead of per user. I guess sounds more appropriate for your use case. You can just start with the lowest tier and upgrade your way up regarding of the computational need you will have.

I see they are mentioning 1 hour
CPU time,
Do you know how this will work exactly, what they mean by 1 hour, 1 hour for Processing queries ?

The CPU time is consumed by HTTP requests. Refer the following blog:

Yes, I think this will be fair