What happens if your Plus account reverts to a Free account?
If your account is over the storage capacity for a free account, it will become locked until you upgrade to a new Plus subscription that will cover the required storage capacity.
If your account is not over the storage capacity for a free account, you will still be able to edit, share, and display all of the images on your account. However, you will see ads again when you're logged into your account. Also, bandwidth limits will apply.