A service plan is a named option that can be associated with a namespace. This option determines how HCP manages the objects in that namespace. Service plan names are system specific.
When creating a tenant, the HCP system administrator specifies whether the tenant is allowed to associate service plans with namespaces. HCP system administrators can change this setting from not allowing these associations to allowing them. However, they cannot do the reverse.
The service plan you select for a namespace should match the expected usage pattern and properties for that namespace. For example, if the purpose of the namespace is to store objects that most likely will not be accessed again, you would choose a service plan with a description indicating that the plan is intended for archiving.