Relationship Between Plans and Subscriptions

Normally, a subscription is associated with a service plan, and this
association is reflected in a list of subscriptions: each subscription
name contains the service plan name in brackets at the end. The amount
of resources and services provided with a subscription can be extended
by associating the subscription with add-on plans. A subscription can be
associated with several add-ons, but each add-on can be added to the
subscription only once.

It is also possible that a subscription may not be associated with a
service plan, and so it cannot be associated with any add-on plans:
add-ons are only added to a “main” service plan. We call such
subscriptions custom subscriptions, and their names are extended with
“(Custom)” in the list of subscriptions. Having a custom
subscription may be useful if you want to provide services on specific
terms that are different from the usual offerings in your business
model.

You can change the association between a subscription and plans at any
time as follows:

• Associate the subscription with another service plan.
• Add and remove add-on plans.
• Remove the subscription association with the service plan and
  add-ons.

States of Subscription

Subscriptions associated with a particular plan are synchronized, or
synced, with it: any changes made to the plan are automatically
applied to all its subscriptions. This is true for all kinds of plans:
service plans, their add-ons, and reseller plans.

Plesk allows the following deviations from the default subscription
state (active and synced with the service plans):

• Locked state, which means locked for syncing, indicates that a
  subscription is excluded from syncing with the associated plans.

  A subscription gets locked if you change the parameters of the
  subscription, without changing the associated service plan. Such
  locking secures your customizations so that they are not overwritten
  the next time you change the plan and all its subscriptions are
  synced.

• Unsynced state indicates that some services or resources offered
  with the associated plans cannot actually be provided with the
  subscription.

• Suspended state. This state is not related to the synchronization
  of a subscription with the service plan, but it affects the behavior
  of websites. Plesk suspends subscriptions automatically if their
  expiration date passes. In addition, you can suspend a subscription
  manually. To learn more, see Managing Subscriptions.