i'm assuming you use a trigger or distance condition in a script to activate the addaction.
name your action first:
NAME = player addaction ["take hostage", "hostage.sqs"]
Then have a trigger that activates on the following:
player distance hostage >=5
with the activation as:
player removeaction NAME
remember to set the trigger to repeatedly for both this trigger and the one that activates the action as available
make sense? I'm english but my english still sucks!!