This is an icon representing plus one month. It has a calendar made up of two differently sized rectangles. There are two small rectangles on the top of the calendar where the rings would be and it has + 1m written in the center.
This icon is a part of a collection of Plus 1 Month flat icons produced by Icons8. Icons follow the guidelines of iOS, Windows, and Android and are designed by a single designer, guaranteeing the consistent quality.