Launch the NI License Manager. You can do this by searching for it in the Start Menu, or by looking in the National Instruments folder in the Start Menu.
Press Activate Software.
Log in with your NI Account. If you don't have an account, you can create one here.
Press Activate. If you get an error regarding the Student Edition, press Cancel.
After finishing the activation process, you should see that both MultiSim and Ultiboard are activated. This means you're all set! You can now close the NI License Manager.