[WorldCraft]

If you put your paid users into their own usergroup, go to the Usergroup Manager and edit the usergroup. In Username HTML Markup, in the left box place your <img src="" /> html in that box and save. If you are setting this as an additional usergroup and not primary, you will need to edit each user's profile in the AdminCP and set the usergroup in the 'Display Usergroup' drop menu so the image will appear. This will make the image appear virtually everywhere where the user's name appears.

If you want it to show on posts only you can use this condition in your postbit or postbit_legacy template (depending on which one you are using) instead.

Find: {vb:raw memberaction_dropdown} and one line above this place:

<vb:if condition="$post['usergroupid'] == X"><img src="" /></vb:if>

Replace X with the usergroup id of the paid users and fill in with your image.