Expiry
Expiry is the point after which a price-conditional recommendation no longer applies.
In plain English
A conditional recommendation is a claim about a price as well as an outcome, so it has to end. Once the stated terms are gone the recommendation is spent, and treating it as still live turns it into a different bet than the one published.
Example
An instruction valid at -3 or better is no longer valid once every available book has moved past that number.
Why it matters
Recommendations without an end point can be quietly reinterpreted after the fact to fit whatever happened.
How V8 uses this term
V8 shows the current status of an instruction, including when it is no longer available, rather than leaving an expired claim looking live.