Torchlight II has been featured as a "Free Game of the Week" multiple times. If you add it to your library during these events, you keep it forever.
If you are looking for a "free link" or a product key for Torchlight II torchlight 2 runic key free link
For more information on item IDs and console commands, you can check the official Torchlight 2 wiki or community forums. Torchlight II has been featured as a "Free