May we use Oracle licenses which have been purchased under ULA (Unlimited License Agreement) in a cloud environment?
Yes, licenses purchased under ULA may be used in so called Oracle Authorized Cloud Environments. Those are Microsoft Azure, and Amazon EC2 as well as Amazon RDS. Licenses that have been purchased under ULA and have been used in an Authorized Cloud Environment may not be included in the certification at the end of the term of the ULA.
Source: Whitepaper_Oracle_Licensing Oracle Software in the Cloud Computing Environment (the document may not be published, but can be accessed from the following url: https://www.oracle.com/us/corporate/pricing/cloud-licensing-070579.pdf), retrieved 2018-01-09