This question has been asked via email several times and we thought the answer was useful enough to post here (see below)
Yes. We would be happy to send you a PayPal invoice for Plus membership.
However, due to the overhead of us having to manually do this, the minimum duration is 12 months.
If you email your Hooktheory username to email@example.com we will email you a PayPal invoice 12 months of Hookpad Plus.
Once the invoice is paid, we will grant you Hookpad Plus access.