Problem: Usergroup "Registered" is set to
Moderate this group's images = Yes
Moderate this group's posts = Yes
Now the user purchases a premium membership through paid subscriptions, which gives a secondary usergroup that is set to
Moderate this group's images = No
Moderate this group's posts = No
... and this won't work as Yes overwrites No
Suggestion: Make these category settings and have a usergroup option
Use Category Moderation Settings - as vBulletin does it for forums.