Cashboard limits each account plan to a number of active projects.

Active projects are projects that are being worked on currently. You may create tasks, log time, and create invoices for them.

You are not charged per-active-project, rather for the number of active projects your account plan can have. This number is a flat rate.

When you create an estimate you are creating a potential project. You are not charged for potential projects. Only if your client accepts an estimate and you activate the project for that estimate is it counted against your active project count.

Closed projects may not be worked on in any way. This means no time may be logged, no tasks edited or created, and no invoices generated.