Cookie Lifetime Discrepancies in Platform Terms

Introduction

Cookie duration is one of the most important metrics affiliates consider when evaluating programs. A "30-day cookie" should mean that affiliates receive credit for any conversion within 30 days of the initial click. But what happens when stated cookie durations don't match actual behavior?

Our investigation found significant discrepancies between advertised cookie lifetimes and actual tracking persistence across multiple platforms. These discrepancies have real financial implications for affiliates and raise questions about disclosure practices in the industry.

Methodology

We tested 18 affiliate platforms with stated cookie durations ranging from 7 to 90 days. Our testing methodology:

• Created test affiliate accounts on each platform
• Generated affiliate links and tracked initial cookie placement
• Monitored cookie persistence at regular intervals
• Tested conversion attribution at various points within and beyond stated windows
• Used multiple browsers and devices to verify results

Key Findings

Finding 1: Early Cookie Expiration

Several platforms set cookie expiration dates shorter than their advertised duration. In some cases, cookies advertised as 30-day expired after just 7 days.

// Advertised: 30-day cookie
// Actual cookie header:
Set-Cookie: aff_id=123; 
  expires=Thu, 10 Mar 2026 00:00:00 GMT;
  // Only 7 days from click date
  
// Expected expiration should be:
  expires=Wed, 03 Apr 2026 00:00:00 GMT;

Finding 2: Session-Based Overrides

Some platforms use session-based tracking that overrides persistent cookies. When users return via different channels, their session data takes precedence over the stored affiliate cookie.

Finding 3: Cross-Device Gaps

Only 3 of 18 platforms tested offered true cross-device tracking. For the remaining 15, a user clicking an affiliate link on mobile and converting on desktop would not be attributed to the affiliate.

A '30-day cookie' is only as valuable as its ability to track users across their actual purchase journey, which increasingly spans multiple devices.

Platform Analysis

We categorized platforms based on the alignment between their stated and actual cookie behavior:

Technical Factors

Several technical factors contribute to cookie lifetime discrepancies:

ITP and Browser Privacy Features

Safari's Intelligent Tracking Prevention (ITP) and similar features in other browsers can limit cookie lifetimes to 7 days for cross-site tracking. However, some platforms don't disclose this limitation to affiliates.

Server-Side vs Client-Side Tracking

Platforms using server-side tracking may have different effective durations than their client-side cookies suggest. The disconnect between these systems is rarely explained to affiliates.

Attribution Model Interactions

Last-click attribution models can effectively nullify cookie duration when users interact with other marketing channels before converting.

Consumer Impact

While this investigation primarily concerns affiliate marketers, consumers are also affected by cookie tracking practices:

• Privacy Expectations: Users may believe clearing cookies removes tracking, unaware of server-side persistence
• Disclosure Requirements: Cookie policies may not accurately describe actual tracking behavior
• Cross-Device Tracking:Users may not realize they're being tracked across devices through login-based systems

Recommendations

For Affiliates

• Test cookie behavior independently before committing to programs
• Ask specific questions about ITP handling and cross-device tracking
• Request written clarification of attribution models

For Platforms

• Clearly disclose effective cookie durations under different browser conditions
• Explain how attribution models interact with cookie tracking
• Provide transparency reports on tracking accuracy

For the Industry

• Establish standardized disclosure requirements for cookie terms
• Create third-party verification services for tracking accuracy
• Develop industry guidelines for fair attribution practices