How to revoke "SMS Services that cost you money" permission? I have an Android 6, Samsung S6 smartphone and today I bought a tram ticket via SMS.  Before sending, a warning popped up asking if I wanted to grant the Messages app the permission "SMS Services that cost you money".  I assume this was because the SMS ("Premium SMS") is overcharged (by the price of the ticket), since the app never asked for this permission before sending a SMS.

I replied Yes, since it was a legitimate purchase, but I was in a hurry and involuntarily I ticked the option "remember my choice".

Now I would like that Android keeps asking me before sending Premium SMSs, since it's a security risk, but I couldn't find a setting to disable this option.  Is this possible?  Or the only way is to hard reset my phone and reconfigure it from scratch?  I can't believe Android doesn't offer this option.
You can choose another setting by going into Settings > Applications > Applications Manager > More (top right) > Show System Apps > Message Service (rather than Messages) > 
Tap 'Send Premium SMS' > Select Ask, Never Allow or Always Allow.

On more recent versions of Android (Nougat V7) the setting is at Settings > Apps > Application Manager > More (top right) > Special Access > Use Premium SMS services (may be listed as Use Premium text message services) > Select Ask, Never Allow or Always Allow.