We still maintain the Lifetime subscription. It's possible that your subscription is on a different Google account. Follow the steps below to restore it.
1. Uninstall drupe from your device.
2. Open the Play Store app.
3. Make sure you're using the right account by tapping the Menu icon (top left corner) and checking the email address.
4. If the account is not the right one, change it by tapping the small arrow next to the email address and selecting the right account.
5. Open device settings -> Apps -> Play Store -> Storage & cache -> Clear cache.
6. Search for drupe in the Google Play store.
7. Download and install drupe.
If the steps do not help, feel free to contact support at hi@getdrupe.com.