I can't seem to find a good example outside of 3rd party materials right now and pending GM or Dev input I figured I'd ask here. The example I'm specifically looking at is the Dart Gun I spell from Ponyfinder with a 24 hour duration that uses a focus component that is an armlet worth at least 25g. If that armlet were removed for some reason (stolen, confiscated, handed to someone else, etc) would the spell duration end at that point or is the focus component only needed for the initial casting? If it were a Concentration spell I could see it needing to stick around, but IDK otherwise. Anyone have any official rulings on this?
Losing a spell's divine or arcane focus component after casting the spell typically has no ill effects on the spell
Unless the spell says otherwise, a spell's components only need to be satisfied during the spell's casting: On Components says, "A spell’s components explain what you must do or possess to cast the spell," and among those components is a focus component. Later, Casting Time details when a spell comes into effect, ending its casting, and no longer mandating the spell's caster satisfy the spell's components.
Thus in the same way that a spell must say that it requires the caster to gesture continually throughout its duration or else the spell's duration ends (none to my knowledge do, by the way), a spell must also say that any focus component is required throughout the spell's duration and explain the consequences of its loss.
For example, the shapechange spell has as its focus component a jade circlet with a price of 1,500 gp, but after casting the spell the caster can do whatever with that circlet without worrying about the spell ending prematurely or any other effects. (Using the shapechange spell to change form may cause the circlet to meld with the caster—see Transmutation on Polymorph—, but casting the spell then doffing the circlet then taking a free action to change form using the spell's effect is totally legit.) Compare this to the consequences described for destroying the focus of the magic jar spell while the caster's life force is inside the focus.