Are you using WooCommerce? Why don't you connect your shop to MailerLite? In this video, you'll learn how to do this.
Start by navigating to the Integrations section from the top-right dropdown menu. Find WooCommerce and make sure to turn on the integration. Then copy the API key.
Now go to your WordPress website and make sure you have WooCommerce installed. Go to the plugin area and look for MailerLite. Click the WooCommerce - MailerLite integration and install the plugin.
Once installed, click Activate. Now you can go to the WooCommerce settings within WordPress. Here is where you paste the API key. Then save the changes.
Now when you go back to your MailerLite account, you see that when you go to Subscribers and then Fields, some new custom fields are automatically added. These are needed for the integration.