You simply can Instantiate the effect, it plays, and destroys itself once done.
Please note that the product is the effects (particle systems, objects, textures), not the example scene. The scene's purpose is to showcase the effects. While the example scene is also attached, I bear no responsibility that it will be useful to you. There is a DEMO VERSION of the pack (3.5 unitypackage format), that contains just a few effects, the readme file and the scene.
Particle Systems are naturally hard to scale. There is a wonderful tool that helps in that, PARTICLE SCALER.
Comments, questions? Feel free to write to kalamona01 at gmail dot com.