The Pro version of OSpam-a-not allows you to explicitly select which forms to protect from spam. You can find this feature inside the plugin on the "Form Contexts" tab:

With this feature, you can select protection for specific forms.

The easiest way to find the contexts for each form is to check the OSpam-a-not logs. When logging is enabled, form contexts can be found in the log when a form has been blocked. Here are some sample entries:

• Joomla login form: com_users.user.login
• Joomla registration form: com_users.registration.register
• Joomla user profile forms: com_users.profile
• Joomla privacy requests: com_privacy.request.submit
• Joomla password resets: com_users.reset.request