iPhone and Android monthly payment - best ways

I have to write monthly payment for these two platforms for one开发者_如何学C of my clients.

My question is:

1. Can I use PayPal payment for iPhone for this kind of payment? (not buying anything for iTunes, just paying subscribtion).
2. What other payment services providers would you recommend? (for example: In-app purchase for iPhone, something else for Android, etc.)
3. What can you recommend me to use as a library (I saw PayPal X, is this good for example?)

thanks in advance, Danail

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1. Yes. We can use Paypal.

2. Other services include:

   • Google Checkout
   • Amazon Payment Services

3. Paypal X is good