Well that clutch is rated up to 13hp so your good there. The thing I don't like about the Max torque 1" clutches is they only seem to be available with fairly large-sized/tooth-count driver gears.
How long the clutch lasts will pretty much depend on your final gear ratio, how heavy you and your kart is, and where you ride. If you only ride on flat surfaces like parking lots, that clutch would probably last for years and years. If your going to ride off road (and try to climb hills) where the clutch will have to spend much more time slipping before it fully locks in, you'll find most any centrifugal clutch would wear out much quicker.
Your final gear ratio might be very critical to how long your clutch lasts so I've got a few questions for ya here:
Northern Offers 1" clutch models with 3 different choices of driver gears, which one did you order?
How many inches tall are your karts rear tires?
Does your kart have a jack shaft by any chance? (if so, what tooth count gears does it have?)
How many teeth does your current rear sprocket have?
How much do you weigh and whats the approximate weight of your kart?
And finally where will you be riding your kart?