I've been charged before the trial expiration
When you install the app, you need to accept the charge. However, you will not be charged until the trial period expires (this is how the Shopify standard trial model works).
When the Shopify system asks you to accept the recurring charge, all information about the charge, the trial, and when you will be charged are displayed clearly on your screen:
During the trial, at the top of the app preferences page, you will also see a message like the following:
You will not be charged if you uninstall the app before the trial period ends.
You may also receive a notification email from Shopify about your payment. Don't worry, that means that the payment has been approved, but you will not be charged until the trial period ends.
Please note that payments are managed directly by Shopify. Shopify, not us, who charges you and then transfers our part to us. You can contact Shopify support for any questions related to the app charges.