I am developing a web app whereby registered users will have a dashboard where they can manage their ads, after payment... so they have to register and pay to use the app. The registration processes I am working with is as follows:

 1. Register to use the site (name, username, password and email fields)
 2. Activation link is sent to their email.
 3. When activation link is clicked, they are directed to payment platform to pay for the service.
 4. After successful payment, users are directed to their respective dashboard to create ads.

Is this process simplified enough? How can I make it even simpler?