Android Traditional Lottery App Development

I'm looking to create a traditional lottery app for Android. The app should support user registration and login, as well as payment integration.

Key requirements:
- Android platform support
- User registration and login
- Payment integration

Ideal skills and experience:
- Experience in Android app development
- Expertise in implementing secure payment gateways
- Knowledge of user authentication and registration processes

Please provide samples of previous work and an estimate on the time needed to complete this project.