If you are a paid member and you used more space than the max storage limit that your plan gives you, additional charge will be added to your monthly fee. The rate of additional charge is $0.035 per 100MB of exceeded space. The exceed space is based on the peak usage from previous billing date to the day before next billing date. However, if you make a mistake by uploading huge amount of files, you have 24-hour grace period to delete your uploads and it doesn’t count it as a peak usage. (e.g. if you upload 10Gb over 20G free storage and delete 3Gb within 24 hours, you will only be billed for 7Gb.)
This FAQ posted in: Billing
