Spanish to English Law/Patents Law: Contract(s)

I am really having trouble working in the first part of this sentence. Not sure if what I have is the best. Suggestions? Spanish to English. I have included the original context as well as my attempt at a translation for reference.

Sus facultades representativas resultan de su cargo de Administrador Único, para el que fue nombrado en virtud de decisión del socio único de dicha mercantil, constituido en Junta General, tomada el día 25 de octubre de 2013, en cuyo acto aceptó, por tiempo in­definido, según consta en escritura autorizada por el notario de Valencia

XXX is a duly authorized representative, being named Sole Administrator by virtue of the decision made by the only member of said company, during a General Meeting, on the 25th day of October of 2013, in which the act was accepted, for an indefinite period, as recorded in the instrument authorized by the notary