I purchased a PRO license a few months ago on my Google account - and absolutely love it

I don't mind paying for it again, it's easily worth it. But it seems to be impossible to sign up within the app without having a Google account. The account selection dialog pops up for a split second and then immediately disappears when it realizes (I'm guessing) that none of those accounts are associated with Google Play.
Do I have any options at all here? Like I said, I don't mind paying for it again via PayPal, I just need some way to do it without having Google Play on my phone.
Thanks!