For everyone’s info, here is the response I received from PP
“Dear Mr FDOS
Thank you for your email regarding your Priority Pass membership dated 06 Nov 2015.
I can confirm that your request to cancel your membership has been received and is currently being processed.
You will receive a cancellation confirmation email once we have completed processing your request, which should be within 48 hours (Monday-Friday).
Priority Pass obviously regrets your decision to cancel your membership, should your circumstances alter and you decide to re-join as a member, please do not hesitate to contact us.