Add fields to a product · aMember Pro Docs

Add this code to site.php file:

//Add Text Field
Am_Di::getInstance()->productTable->customFields()
    ->add(new Am_CustomFieldText('field_name', 'Field Title'));
//Add Select Field
Am_Di::getInstance()->productTable->customFields()
    ->add(new Am_CustomFieldSelect('another_name', 'Another Title', null, null, ['options' => ['1' => '11', '2' => '22']]));

List of available additional field types:

Am_CustomFieldHidden
Am_CustomFieldText
Am_CustomFieldTextarea
Am_CustomFieldSelect
Am_CustomFieldMulti_Select
Am_CustomFieldRadio
Am_CustomFieldCheckbox
Am_CustomFieldSingle_Checkbox
Am_CustomFieldDate

To retrieve value of such field for specific product from product record you can use the following code:

$product = Am_Di::getInstance()->productTable->load(1); //retrieve product record with id = 1
$product->data()->get('field_name');