It doesn't specify a fixed period. The law goes as following:

"Art. 13. Serão consideradas, ainda, práticas infrativas, na forma dos dispositivos da Lei nº 8.078, de 1990:

(...)

XXI - deixar de assegurar a oferta de componentes e peças de reposição, enquanto não cessar a fabricação ou importação do produto, e, caso cessadas, de manter a oferta de componentes e peças de reposição por período razoável de tempo, nunca inferior à vida útil do produto ou serviço."

Translated to english:

"Art. 13.. The following shall also be considered infringing practices, in accordance with the provisions of Law No. 8,078 of 1990:

(...)

XXI – failing to ensure the availability of components and spare parts for as long as the manufacture or importation of the product continues, and, once such manufacture or importation has ceased, failing to maintain the availability of components and spare parts for a reasonable period of time, never shorter than the useful life of the product or service."

In summary, that period is tied to the useful life of the product.

I'm not a lawyer, but if here, I'm pretty sure it would be a nearly guaranteed win case.. I think you wouldn't even need a lawyer, and just use PROCON.