License verification not working for in-app purchases

Describe the bug
v0.3.1.240913 added support for license verification however it only works with apps with upfront payment such as Tasker.

Apps with in-app purchases cannot have it's license verified even if it has been purchased previously such as Quick Cursor or VTube Studio, it will only produce a "You already own this item" error.

To Reproduce
Steps to reproduce the behavior:

1. Install app with IAP for example Quick Cursor
2. Agree to ToS and enable permissions
3. License isn't verified, click option to enable Pro features
4. See error "You already own this item"
5. Cry

Expected behavior
License should be verified.

Screenshots

Screenshot

System
Android Version: 13 and 14
Custom ROM: LineageOS for microG 20 and 21

microG
microG Core version: 0.3.1.240913
microG Self-Check results: All ticked

Additional context
Saw #2254 and decided to make a generic bug report since I can confirm it affects all paid apps that use IAP instead of upfront payment.

To get full context, was the license you want to restore

1. bought with microG Service and microG Companion,
2. bought with microG Service and Play Store, or
3. bought with original Play Services and Play Store

on

1. the same device, or
2. another device?

Quick Cursor and VTube Studio was purchased with MicroG and Play Store on a different device from the one being used now.

No source file, test, or entry point is named. Start by reproducing the problem with Quick Cursor or VTube Studio and compare the reported purchase contexts, then trace the license-verification flow; done means previously purchased in-app products verify without the “You already own this item” error.