See - http://sc.judiciary.gov.ph/jurisprudence/2012/june2012/6368.htm
"x x x.
It is first worth mentioning that the respondent’s defense of prescription is untenable. The Court has held that administrative cases against lawyers do not prescribe. The lapse of considerable time from the commission of the offending act to the institution of the administrative complaint will not erase the administrative culpability of a lawyer. Otherwise, members of the bar would only be emboldened to disregard the very oath they took as lawyers, prescinding from the fact that as long as no private complainant would immediately come forward, they stand a chance of being completely exonerated from whatever administrative liability they ought to answer for.[25]
x x x."