When a visitor follows a link or banner from your site, 2Checkout keeps track of your Affiliate ID for 120 calendar days. That's 4 months during which any order placed by the same user guarantees your affiliate commission.
You will get your commissions every month, either transferred to your 2Checkout prepaid debit MasterCard or sent via wire transfer, check or PayPal.
Use every available channel of promotion you have - website, newsletter, etc! Remember - the more referral links you create, the more chances you have to make money from your website!