I lose a DoW and agree to do whatever you tell me to do.
That effect lasts until one of us dies? Or until we're separated for x-distance or x-amount of time? Or ... ?
You can get the answer from the free rulebook that you can download here:
https://www.drivethrurpg.com/en/product/98542/burning-wheel-gold-hub-and-spokes
It's on p 32:
One of the most important aspects of ability tests in game play in Burning Wheel is the Let It Ride rule: A player shall test once against an obstacle and shall not roll again until conditions legitimately and drastically change. Neither GM nor player can call for a retest unless those conditions change. Successes from the initial roll count for all applicable situations in play. . . .
The successes of those rolls ride across the entire situation, scene or session.
I posted an example upthread, in reply to you, of conditions changing: the PCs faffed around for too long in the catacombs (determined because they failed a test while
working carefully).
The Codex also gives some examples, on p 150:
You discover new information; you're deceived or betrayed; you lose your horse/ship/flying carpet; the weather takes a sudden turn for the worse; you're lost; you're found; your finery is covered in <excrement>/blood/mud; you learn a new spell or school of magic; your precious possessions are stolen; you discover a powerful artifact; you earn a new trait; a miracle happens.
Obviously this is not a checklist - it's pointing to the sorts of things that
players might stake and that, if staked and forfeited (or won), then the old outcome is up for grabs. This is as I explained in the Halika case: by having their PCs take their time (by working carefully), the players are implicitly staking that the sleeping potion they had administered to Halika might wear off.
The Codex also says this, by way of clarification (p 181):
Conditions that don't generally count as significant or drastic: you're superficially or lightly wounded; you change a Belief; you change an Instinct; you ask, "How about now?"; or you fail another test.
If you're wounded so badly that the skill or ability with which you overcame an obstacle is reduced to zero, then Let It Ride doesn't apply. Otherwise, wounds should count as a change of conditions for Let It Ride.
Ultimately, as
@Old Fezziwig has also posted, what counts as an appropriate change in the conditions that underpin the outcome is contextual. In my experience, if the players think that the conditions have, or haven't, changed, they will let me know! And then we can talk about it.