Commission is applied off of all payments received. Commissions are a percentage. So, if the trial is a free trial, then there is no commission. However, if the trial is a small amount (like $1 trial for 3 days), then the commission is applied as a percentage of the amount of the trial payment. So, in our $1 trial example, if the commission is 20%, then the commission amount from the trial would be $0.20.
To test commission assignment without doing a real payment you will need to manually add a payment.
To add a payment manually, go to ~wmtsystemurl~/admin/members in the members area and click on the billing history icon for the member you want to add commission for.
In the popup click the Add Payment link.
Enter a payment amount and date. For Type and Transaction ID you can enter anything or leave blank as it doesn't affect test results.
To apply the payment visit: ~wmtsystemurl~/admin/applyaffiliatepayments.php