After successful installation of the plugin, you need to activate it’s license. When you buy the PRO version then you will receive a license key on your email or you can get this license key after login to your account on Trusty plugins site. Link to follow:- https://trustyplugins.com/my-account/.
After getting license key you have to activate it from WordPress admin panel. To activate follow WordPress Dashboard >> CAF License. Enter your key and email address and click on Activate.
Important:- Without activation of Category AJAX Filter PRO plugin, all PRO features can’t be enjoyed. You can find Activation key on your Email address.