You enrol to "Try Free for 30 days" and get all the top paid-plan subscription features for Free for 30 days without any payment-card registration. At the expiration of the trial, your account will be reverted to Free with your data intact, conforming to the Free plan quota and limits, as seen in Pricing (e.g. in case you have exceeded the Free storage limit of 300MB, you will be requested to remove some files so that you comply with the Free plan limit).