The local traffic in Stockholm is owned by SL (Stockholms Lokaltrafik). They are in charge of the subway, busses, trams and commuter trains. As a student you are entitled to the student discount at SL, as long as you study for at least 75% per semester. In order to use the student discount legally you need a valid student ID – your Mecenat card with a SL-logotype on it. All registered students at KI will get a Mecenat card sooner or later, but as a member in Medicinska Föreningen you will get a specially designed one that gives you all our exclusive discounts, plus all the regular ones from Mecenat of course.
It takes about 2-3 weeks to get the Mecenat card after it has been ordered but you´re probably going to want to use the student discount at SL before that. To do this without risking fines you can come to the Medicinska Föreningen office and collect an SL-certificate or download the Mecenat card as an application to your smartphone from mecenat.se
Remember that you have to carry a valid student ID (Mecenat card or SL-certificate) with you at all times when you travel with the SL student card to not risk fines of SEK 1200.