Not worth the hassle - avoid
After switching iPads, my Premium access disappeared. I've been trying to get my this restored, but the developer is near-impossible to contact, as the contact form on their website is broken and the only way to reach them is via GitHub. Now, after the best part of a week, my multiple attempts at contact are going entirely ignored with no hope of a resolution, so unless this is resolved I have no choice but to leave a review to ward others away.