This is an authorization charge for your yearly/bi-yearly license:
When a yearly account is within 30 days of renewal or a biyearly account is within one year and 30 days of renewal, Backblaze will run a brief authorization of $10 ( or international equivalent) to make sure the card details are still valid.
Depending on your card provider, this may show up as simply an authorization, or a charge and then refund/reversal. It should automatically clear itself immediately, Please look in the credit area of your statement.
You can view your next billing cycle by going to https://secure.backblaze.com/user_signin.htm and clicking 'Billing'.