If you simply need to open or convert Civil 3D 2013 files, use the free (still available from Autodesk).

AutoCAD Civil 3D 2013 is a legacy civil engineering design and documentation software that supports workflows. Released on March 27, 2012 , this version introduced significant performance improvements for 64-bit systems, offering faster visual styles and screen rendering compared to its predecessors. Key Features of the 2013 Release

At its launch, the 2013 version introduced several core improvements for civil infrastructure: Autodesk software is reaching the end of activation

AutoCAD Civil 3D 2013 was a landmark release that transitioned the civil engineering community into a modern 64-bit drafting environment

Just then, Raj walked in and saw Rohan's concerned expression. "What's wrong, man?" he asked. Rohan explained the situation, and Raj cautioned him against downloading pirated software. "It's not worth the risk," Raj advised. "Why don't we try using the free trial version of Autocad Civil 3D instead?"

Streamlined project management and version control for large teams. Modern Alternatives