Provider puts some non-free subscription on Administrative Hold. Will subscription be billed for the period it is on hold? When Billing order will be generated?
In general, subscription that has been successfully provisioned is deemed to consume Provider's 'resources', even if its service is on hold (stopped).
That is why subscription will still be billed for resource overusage and plan/resource recurring fees for the period while it is on hold.
However for subscriptions being on hold no orders are generated. Billing / Renewal orders will be generated soon after subscription is released from hold when it will be a time for renewal / billing. (Renewal order is usually generated the next Daily Billing, and Billing Order generated on the nearest Account statement day.)