If you cancel your payments for the Extra and Pro account, your current surveys and polls will be kept, but any new content that you create will be limited to the features of a free account. The applicable limitations ((for example limited responses per month and removal of Captcha voting protection)) will apply to your existing content , too.
If you deactivate your account from Account Settings, your profile and data will be invisible for other users, but your data will be saved and you can always reactivate your account. All of the surveys and data will be available to you again.
Posted in: Account