When you register your details to offer 'Other Services' here, you should click the 'Specify Now' link and tick the boxes next to each service that you are offering.
There is a nominal daily fee for members registered as Other Services: 1 credit for the first category and 0.10 credits for each category thereafter, per day. At midnight each night, your AdultWork.com credits account will be debited based on the number of categories you have chosen.
You must have sufficient credits to cover all of your category selections, otherwise, you will not be debited and your profile will not appear. If you need to buy credits now, you can do so here.
If you deselect categories you will not be refunded for the remaining portion of the day, although if your total number of categories goes above what you've been charged for, you will be debited within 20 minutes. (This time lag gives you the opportunity to change categories without being charged.)
Members that are featuring their profiles will not be charged on the days that their profile is featured.
In summary, you will be charged at around midnight every day when a charge is required, except on your first day or when your profile first becomes valid for display, when you will be charged within 20 minutes. (This saves you from having to wait until midnight to appear on the Site.)
Further information is available here.