One bill for the suite
Billing belongs to the organisation, not to each product. You pick a plan once, and that plan decides which products your organisation can open.
Credits
Some work is metered rather than flat-rate — generation, translation and other tasks whose cost depends on volume. Those consume credits, which are shared across the organisation's products. A busy month in one product therefore does not force an upgrade in all of them.
Credits can be topped up as a one-off pack from the billing page, without changing plan.
Invoices and payment
Invoices are issued to the organisation and available from the billing area. Changing plan takes effect immediately; the difference is prorated on the next invoice.