Gain a keyword - how long does it last?

Rules Questions: Doomtown
1

Abraham’s Crusader outfit says:
“Noon, Boot: One of your dudes gains the Deputy keyword.”
Is the keyword gained permanently?
Or does the dude lose it at the end of sundown because of the “Noon boot” part?

Is there a generic rule concerning “gain” duration when not specified on the card?

For example on Turtle Gard spell, it is explain as such: “All dudes in your posse gain the Harrowed keyword until the end of this round” so the ending is clear.

2

Thanks for the question! End of sundown:

P. 17 of online rulebook:

Unless otherwise noted, the effects of Noon abilities last through the end of the Sundown phase.