depends on what your doing google dont allow payment methods outside of their own in app stuff im sure. https://play.google.com/about/monetization-ads/payments/ as long as it is ok you can use html and redirect to your own php script and login form on a web server.
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https://play.google.com/about/monetization-ads/payments/
as long as it is ok you can use html and redirect to your own php script and login form on a web server.