For CrateDB Cloud, there are currently four plans: Development, General Purpose, IO Optimized and Storage Optimized. The first is intended for a trial of CrateDB Cloud, and does not offer 24/7 support. General Purpose is, as the name suggests, for most use cases. IO optimized is for users requiring more capacity for queries and ingests relative to storage, and Storage Optimized for users wanting the reverse.
In order to simplify billing, CrateDB Cloud uses DTUs (Data Throughput Units). A DTU is a plan relevant hardware configuration that can be linearly scaled along scale units. The DTUs per hour actually used are what Crate.io bills its customers (via Azure).
For a more detailed explanation of the CrateDB Cloud plans and how DTU-based billing works, please refer to this overview in the Documentation.