Cookie duration (or cookie window) determines how long after clicking an affiliate link a customer can convert for the affiliate to receive credit. Common cookie durations: - 24 hours (short) - 7 days (common) - 30 days (standard) - 60-90 days (generous) - Lifetime (rare) Cookie duration considerations: - Product type and sales cycle - Average time to purchase - Competitive landscape - Program attractiveness Cookie tracking challenges: - Cross-device tracking - Cookie blocking/deletion - Privacy regulations - Safari ITP restrictions Best practices: - Match duration to sales cycle - Communicate clearly - Consider first-click vs last-click - Account for privacy changes