You can setup cookie life time from:
Magic Affiliate –> Settings –> General Settings –> Cookie Life(Days):
Cookie life time for tracking a sale. Keep within 30 days for best result.
If you set up the cookie lite time 30 days. A client clicks an affiliate link and purchases / registers your website in 30 days, the related affiliate earns commission. If the client purchases /registers your website after 30 days, the affiliate cannot earn commission.