GoAffPro provides you with the option to disable new affiliate registrations for your affiliate program.
To disable new affiliate registrations, go to the General section in the Settings tab of the GoAffPro admin panel.
Settings > General
Here, go to the Affiliate Registrations section.
Now, uncheck the "Allow registrations from affiliate page" box.
Uncheck Allow registrations from affiliate page box
After this, when affiliates try to register for the affiliate program, they will be displayed the "We are not accepting registrations at this moment. Kindly check back later" message on the Create Account page.