I believe you will be billed:
https://www.prioritypass.com/en/conditions-of-use
Lounge visits are subject to a per person per visit charge. Where applicable (dependent upon membership plan), all such visits, including those by accompanying guests, shall be debited to the cardholder's payment card by (i) Priority Pass or (ii) the card issuer as per the rates and terms notified by (i) Priority Pass or (ii) the card issuer to the cardholder in respect of their Priority Pass membership.
and
When presenting the Priority Pass card on entering the lounge, lounge staff will either electronically scan or take an imprint of the card and issue a ‘Record of Visit’ voucher to the cardholder or make a log entry. The cardholder must sign the ‘Record of Visit’ voucher, or sign the electronic reader (as applicable), which will also reflect the exact number of accompanying guests, if any, but does not show any per person per visit charge. The charge per visit for the cardholder, where relevant, and that for any guests will be based on the ‘Record of Visit’ voucher/ log submitted by the lounge operator.