When you use the particle-editor you can set the maximum number of particles to create. It's the field below "Particle Texture".The official description is:
"The maximum number of particles that the emitter creates over the emitter’s lifetime. After this number is reached, no more particles are created by the emitter. Enter 0 to remove particle limits."
Also see: Particle Emitter Editor Guide
Of course, you should remove the emitter-node from its parent after it created the maximum number of particles. This can be done by creating an action-sequence that waits for a few seconds and removes the emitter-node from its parent [SKAction removeFromParent].