I don't think I understand correctly what your problem is.
You can only make an API Request if you have an API Key.
If you already have a API Key, you are already a TMDb user.

Which Android APP are you talking about?
Is it any of this list?
https://www.themoviedb.org/apps/category/1/1

I believe @ravi8969 is asking about whether we provide an API to allow users to sign up for a TMDb account. At this time we do not. This is not currently planned due to the security concerns of trusting 3rd party application developers to not log passwords. The only supported method is to send users to our website directly.

Thank you so much for your reply. I understand.