Do I get the commission on all purchases made by the user coming to my site?

Affiliates will only be attributed commission for a sale if the user has made a sale using a DCMnetwork affiliate link/code from your site, (approved site) and converts within the given cookie period and have not crossed the action referral occurrences. Also DCMnetwork works on Last Click attribution model.

The Last-Click Attribution model assigns 100% credit to the final touch points i.e the click that immediately precedes sales or conversions.