Bitrix24 Cloud version is SaaS, it is rented by our users. It is deployed, hosted and maintained by Bitrix Inc. in the Cloud. You can use your Bitrix24 account with a free subscription, or with a paid plan. Please see our plans and tariffs page.
Bitrix24 on premise (self-hosted) version is licensed on "per-user basis". By default, each commercial license key includes 25 intranet users which can be extended by additional user coupons. It is fully customizable (color schemes, layout, menu items, header, footer, etc.) and provided with the full source code. It can be deployed and hosted by the end-user or by Bitrix Partners.