Where to Buy Possession
The first issue of Possession came out July 11, 2018.
DriveThru Comics. Buy issues one at a time for $1.99.
ComiXology. Buy issues one at a time for $1.99 or subscribe to the series (you are only charged when a new issue comes out and you will get an email with a download link).
Europe: Sold by ComiXology. 1,79 € (subscriptions available).
Annual book collections
Each 4 issues will become a book, which you can buy for e-reading or as a bound paper copy.
The first volume will be out late 2018 or 2019.