Result Retention

Task results are stored for 5 minutes after solving. After that, the result is cleaned up and getTaskResult will return UNKNOWN_TASK.

What This Means

You have 5 minutes to poll and retrieve your solved token
After 5 minutes, the task ID is no longer valid
If you need the same captcha solved again, create a new task

Recommendation

Poll every 1-3 seconds. Most tasks complete well within the 5-minute window.