Azure consumption services were made available through the Open programs from 1 August 2014 where you buy a $100 (or equivalent) token upfront to consume services against.
This Azure in Open FAQ contains some interesting facts:
- you must activate tokens within 5 years of purchase;
- you forfeit all your Azure in Open balance if you associate your subscription with an EA;
- and if you get to a zero balance then data is retained for 90 days.
Find the full FAQ here: http://bit.ly/1HdqBwY.