In some Mexican courts, "Por presentado/a" would normally be found at or near the beginning of a court's ruling on a complaint or motion brought before it, e.g.:

Por presentado el C. JOSE ANTONIO JAMAYOTE GARCIA, con su escrito fechado y recibido el día 01 uno de junio del año en curso, por medio de cual, solicita que la demandada sea emplazada por edictos.-
http://www.sgg.chiapas.gob.mx/po2012/archivos/descargas.php?...

Of course, I'm assuming that this is the court speaking here, not the movant; in that case, you'd need to change it accordingly, but that's the gist of it.

As previous questions show, we can also use "pro se" or "in propria persona" instead of "acting on her own behalf."

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Note added at 11 hrs (2019-06-21 02:02:26 GMT)
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Just to explain this a little further, for those unfamiliar with Mexican legal writing, the first request by the movant or complainant at the end of the motion or complaint is nearly always along the lines of:

"A usted juez de [...] atentamente le pido

Primero. Tenerme por presentado/a en términos de este escrito..."

Meaning:
"I respectfully pray that this court: 1) Enter my appearance pursuant to this brief/motion..."