How does it work in practice?
A customer reads a review on a blog, clicks an ad days later and finally buys through a voucher code site. Under last-click, only that last party receives the commission.
Most affiliate networks use this model by default because it is simple to measure and explain.
The advantages
The model is transparent and fraud-resistant: there is always exactly one party that gets paid. That makes settlement and audits efficient.
It is also practical for smaller programmes, because it requires no complex attribution technology.
The criticism
Last-click rewards the final metre of the customer journey, not the party that created the demand. Content partners involved early in the research phase end up underpaid.
That can cause valuable publishers to drop out, while voucher sites ride along on top of the checkout.
What are the alternatives?
Models such as position-based or data-driven attribution divide value across multiple touchpoints. That is fairer, but demands more measurement technology and clear agreements.
A pragmatic middle ground is commission differentiation: higher rates for content partners and lower rates for last-click parties such as voucher codes.