You can check with the Consulado-Geral do Brasil that issued it, but as far as I'm aware all of the VITEM-II Business Visas (while they may be extended by the Federal Police while one is actually in the country) expire upon the end of the visit. Student visas and work visas are also the same way. If you've already worked or studied in Brazil and had a visa in the past, if you've left the country then you need to apply for a new visa to come back in order to work or study in the future. That's why they're called VITEM (Temporary Visa).