For substracting in moment.js:
moment().subtract(1, 'months').format('MMM YYYY');
Documentation:
http://momentjs.com/docs/#/manipulating/subtract/
Before version 2.8.0, the moment#subtract(String, Number) syntax was also supported. It has been deprecated in favor of moment#subtract(Number, String).
moment().subtract('seconds', 1); // Deprecated in 2.8.0
moment().subtract(1, 'seconds');
As of 2.12.0 when decimal values are passed for days and months, they are rounded to the nearest integer. Weeks, quarters, and years are converted to days or months, and then rounded to the nearest integer.
moment().subtract(1.5, 'months') == moment().subtract(2, 'months')
moment().subtract(.7, 'years') == moment().subtract(8, 'months') //.7*12 = 8.4, rounded to 8