We're sorry for the trouble. You can restore your purchase at no additional charge.
Open "Premium" in the settings and tap "Restore (Already Purchased)" (if the Premium screen appears instead, tap "Restore Subscription"). As long as you purchased with the same Google Account, your benefits will be restored. This applies not only to the Lifetime plan, but also to monthly and annual plans within their valid period, which can be restored with the same Google Account.
In rare cases it may not work. If so, please try again, or contact us using the "Contact Us" button at the top right.