This software is available as part of the Microsoft Home Use Program which includes Office 2013 Pro Plus and Office 2011 for Mac.
Choose this option to receive a program code via the campus-wide Microsoft Campus Agreement. This code will give you access to purchase Office from Microsoft via the Campus Agreement's Home Use Program at a cost of $9.95.
Eligible customers are allowed to purchase a single license of either Office Professional Plus 2013 or Office for Mac 2011. See more about the Microsoft Home Use Program here.
This is a perpetual license and does not expire as long as the campus-wide Microsoft Campus Agreement is renewed each year.