If you are planning to stay beyond the permissible duration on your e-Visa to Turkey, once you get to Turkey, you have to apply for a residence permit at a local police station. The eVisa is only granted to travelers who want to visit Turkey for trade and tourism purposes. So, if you have other things to do in Turkey outside of those two things, such as work or study, you will need to submit a new application at the Turkish embassy. Do not overstay your e-Visa without following the appropriate channels, or else you might be fined, deported or banned.