Is a Hostelworld Gold membership locked to one particular account, or can it be used when make booking from separate accounts to get a discount? If the latter, then does Hostelworld invalidate cards that are shared by 'too many' accounts?
I don't have a Hostelworld membership, but I emailed them to see what the official stance is (without anyone risking getting their card invalidated).
From Louise Clark on the customer service team:
Thanks for your email. Gold Cards are registered to one email address so all bookings made with that address will be automatically discounted. You can also enter the Gold Card number when using a different email address and the discount will still apply. This is not limited to a certain number of email addresses.
So it looks like the answer is: enter in the membership number on as many bookings as you'd like from as many email addresses you'd like. :) Happy traveling!