What it applies to
A re-treatment of the same surface later, when the roof has aged again. Not a repair, not a second roof, and not a different treatment on a different building.
The terms set it at 20%, usable once, not transferable to a new owner, and inside 24 months of the warranty expiring. It is part of what the warranty provides rather than a seasonal promotion.
Why a re-treatment is planned for
Every term in the range ends: 3 to 20 years depending on treatment and band, from the Boost bridge at 3 to 5 years to Fortify Elite at 20 years on Good. A roof that is protected today will need protecting again eventually.
Having the next treatment priced on a locked basis makes that a planned decision rather than an emergency one.
How it fits with the score
A re-treatment is quoted against the roof as it is measured on that day, because the band decides both the treatment and the term. The lock applies to the price, not to the band.
That is why the honest sequence is: treat for the band you are in, then re-measure when it is time to treat again.
What it is not
It is not a promise that the roof will need no other work, and it is not a guarantee against price changes in materials over a decade. It is a stated discount on a specific future service, written into the terms.
Ask for the clause to be pointed out in your estimate if it matters to your decision. It is a fair question to raise before signing.
How to use it well
Ask for a re-treatment before the roof is failing rather than after, and the lock is applied to work that protects a surface still worth protecting. Waiting until water is inside turns a treatment decision into a repair decision, and the lock does not change what the roof needs by then.
It is a discount on a service, not a reason to defer care.
Where to find it in writing
The lock is part of the warranty, so it is named in the terms that come with the estimate rather than agreed on a phone. If a future re-treatment is being planned, quote the registration details so the record is matched.