In HitFilm 2 the lifetime panel appeared as a tab with the Media, Controls and Track panel. In Hitfilm 3 I don't see the panel even when selecting a Particle System.
Found that it has to be turned on from the Workspaces.
Don't forget you can save your own workspace layouts using the workspace menu, once you've got it set up how you like. It also makes it easy to switch between multiple layouts depending on your current task.
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