We use Stripe as a billing provider, who manage payments for companies like Twitter, Kickstarter, Lyft, Shopify, Xero and SurveyMonkey. When you first add a card to Stripe that you are going to use in the future, like we do when you sign up for a free trial, they need to make sure it actually exists and is a 'real' card.
What Stripe does is make a request to charge the card $0 – most banks will reply 'ok' and Stripe knows that the card is real and legitimate. Some cards will fail with an error code saying the "charge" isn't possible, and so Stripe puts an authorisation on the card for $1, and then immediately refunds the charge / cancels the authorisation.
This $1 charge seems to occur more often with debit cards, however it does happen with some credit cards. Rest assured that it's not us collecting any money – it is just to ensure that the card is real, and is automated by our billing provider.
As a result of this, some people will have a $1 authorization to Schedugram on their statement when they first register for a free trial. This is NOT a charge and will be removed from your statement. Depending on your bank this can take a few hours or weeks.
We don't charge customers during the free trial – otherwise it wouldn't be free, or a trial. However, we do have to collect payment information upfront. This means that your posts won't be interrupted if you choose to continue your Schedugram subscription, and reduces fraudulent users.
To learn more, please see Stripe's FAQ page on the authorisation charge.