Apple charged me the first of the the 7 days free trial

It just happened the same to me. I forgot that I use the free trial for an app and then downloaded the app again and was offered by Apple and/or the app the free trial again BUT at the same time charged for one year subscription of the app. This app can actually be subscribe weekly, monthly, quarterly, etc but Apple decided to charge one year and saying that the free trial is only for new users... I have read their terms and conditions and have still not found where it is stipulated. Transparency would be nice.