Ill go to auto zone and sell you some of their tint with a lifetime warranty. It doesnt mean 2 years down the road the hardcoat wont start flaking off or the tint wont turn purple. Hell if it does Ill send you another auto zone tint roll. See where Im going with this?
Lifetime warranties are only good through tint shops because the labor required to remove and retint will take twice as long as before. And after a window has been stripped, it is harder to get all of the glue out from edges etc. It's basically a headache if you dont know what you're doing.
There is a reason we are called professionals.