NTLite licenses are permanent, but they do expire. Sounds confusing right?
When you purchase a license, every successful activation is permanent for that HW ID. If you don't change the HW profile (upgrade CPU, motherboard, network adapter), then that copy is permanent.
Why do licenses have an expiration date? The license permanently unlocks all premium features added before the expiration date. New features added after expiration will be locked. What that means is if you're happy with the existing features (or don't need the next major Windows release), then NTLite doesn't require a renewal.
After a newer Windows gets released, you have to re-purchase NTLite (at the renewal pricing) to take advantage of it. Upgrading to a new NTLite version is still useful for expired licenses, because it may contain bug fixes for your old features.
Yes. Edge removal is a licensed feature.