Below is a description of how licenses are utilized by the Quartus® II software, IP cores and ModelSim-Altera Edition software:

Quartus II software:

All Quartus II software processes check for the presence of a valid license, including the Quartus II GUI, Analysis & Synthesis, Assembler and TimeQuest Timing Analyzer. These processes start only if a valid license is available. These processes do not hold or occupy the license, they only validate that one is available.

However, the Fitter checks out a license when it starts, and holds the license for the duration of the Fitter process.

IP cores:

A license for an IP core is checked out when the first encrypted file of the IP core is opened by the Quartus II software for synthesis. This license is held for the duration of synthesis.

The Assembler checks out the license for every IP core to create the programming file and holds it for the duration of the Assembler process.

ModelSim-Altera Edition software:

Once a design unit is loaded by ModelSim-Altera Edition software during elaboration, a ModelSim-Altera Edition license is checked out, and remains checked out until the simulation ends (quit -sim), or the simulator is closed.

A ModelSim-Altera Edition license is also checked out for Wave Log Format File (.wlf) viewing once a waveform is loaded into the simulator, and remains checked out until the waveform window is closed.