Put simply, these are transactions between yourself/your business and AdultWork.com. This can include purchasing promotional facilities or being charged site fees.
For those in the EU, these transactions require Place of Supply VAT. However, by providing AW with your VAT registration details here (Group Managers), it allows us not to charge the VAT on these Business-to-Business transactions under the Reverse Charge Provision.
If you are outside the EU, you may be not required to pay Place of Supply VAT but Place of Consumption VAT may still apply to promotional facilities you purchase depending on your country's interpretation of 'digital services.
Please also see the VAT Information page for more details.