How do you change the Lifetime of a ParticleEmitter?

lft = 0.5 --Change Lifetime here
Aura = Instance.new("ParticleEmitter", LeChar.Torso)
  Aura.Lifetime = "lft"
Aura1 = Instance.new("ParticleEmitter", LeChar.Head)
  Aura1.Lifetime = "lft"
Aura2 = Instance.new("ParticleEmitter", LeChar["Right Leg"])
  Aura2.Lifetime = "lft"
Aura3 = Instance.new("ParticleEmitter", LeChar["Left Leg"])
  Aura3.Lifetime = "lft"
Aura4 = Instance.new("ParticleEmitter", LeChar["Right Arm"])
  Aura4.Lifetime = "lft"
Aura5 = Instance.new("ParticleEmitter", LeChar["Left Arm"])
  Aura5.Lifetime = "lft"

The problem I can see is that you are doing

Aura.Lifetime = "lft";

instead of

Aura.Lifetime = lft;

If you remove the quotes from the variable it will work. The fixed code looks like this

lft = 0.5 --Change Lifetime here
Aura = Instance.new("ParticleEmitter", LeChar.Torso)
  Aura.Lifetime = lft
Aura1 = Instance.new("ParticleEmitter", LeChar.Head)
  Aura1.Lifetime = lft
Aura2 = Instance.new("ParticleEmitter", LeChar["Right Leg"])
  Aura2.Lifetime = lft
Aura3 = Instance.new("ParticleEmitter", LeChar["Left Leg"])
  Aura3.Lifetime = lft
Aura4 = Instance.new("ParticleEmitter", LeChar["Right Arm"])
  Aura4.Lifetime = lft
Aura5 = Instance.new("ParticleEmitter", LeChar["Left Arm"])
  Aura5.Lifetime = lft

2 Errors:

1. lft is a variable , anyhing in quotes( " " or ' ' ) is a string.
2. lft must be a number range

So,

lft = NumberRange.new(0.5) -- Yes this thing does exist

Aura.LifeTime = lft -- no quotes