Help with SQL SERVER 2012 Licence
Purchase Microsoft SQL Server Developer Edition for each of your SQL developers in the exact SQL edition that you need. I would personally go for SQL Server 2014 Developer Edition since service pack one is available.

UPDATE: As of Late March 2016 Microsoft SQL Server Developer Edition is now free.

https://blogs.technet.microsoft.com/dataplatforminsider/2016/03/31/microsoft-sql-server-developer-edition-is-now-free/?MC=Vstudio&amp;MC=SQL&amp;MC=IE&amp;MC=HTML5&amp;MC=JavaScript

Microsoft SQL Server Developer Edition, contains all the benefits of Microsoft SQL Server Enterprise Edition, and must be applied to each respective SQL developer within your organization that uses Developer Edition. That being said, once your developers have a SQL Server developer license, they can develop indiscriminately on as many Developer Edition SQL Servers and databases as you like with as many cores as you like. 

For example, one developer with license can deploy (n...) databases to (n...) SQL Servers with (n...) cores. Another developer within your organization can access all those installations, databases, and SQL Servers provided that they, too, have a developer license. 

Microsoft SQL Server and can literally save your organization thousands to tens of thousands of dollars for development servers--especially since core licensing has gone through the roof. It's a shame that many Microsoft licensing VARs are very misinformed and/or uninformed about Microsoft SQL Server Developer Edition.