You don't need orderID, you need "base orderID" and you can generate the current orderID from startTime and expireTime
From the Android developer ( https://developer.android.com/google/play/billing/billing_subscriptions.html#administering ):
Subscription Order Numbers
To track the transactions associated with this subscription, Google payments provide a basic trading account number for all repetitions of the subscription and indicate each recurring transaction by adding an integer as follows:
GPA.1234-5678-9012-34567 (basic order number)
GPA.1234-5678-9012-34567..0 (first repeat identifier)
GPA.1234-5678-9012-34567..1 (second repeat identifier)
GPA.1234-5678-9012-34567..2 (third repeat identifier)