As defined by OED, Anniversary is,
the date on which an event took place or an institution was founded in a previous year.
Is their any word in the same context which can be used for addressing the events after one month. For instance, I have to congratulate a friend on his marriage after one month.
P.S. I know that we can always keep it simple and convey the most, but I am just curious to know if there is any word equivalent to 'anniversary' but for the time period of one month.