Ways to offer app as free, and still charge users to pay for the service/usage?

I want to make my app free on the Android Market, also the country I live it, is not allowed to upload paid apps yet, neither to download it.

But also I want to charge the users somehow for using it, without Android Market as that opts out the usage. Probably it would be an annual fee.

So I am wondering, if I have a website where users can register, and pay for the membership. Can I use this on the app? So the app will require the user to provide a login for the website, and开发者_Go百科 there will be a credit check, if it allowed to use it it will continue.

What do you say, is this legal according to Android Market rules, and is this possible?

Are outthere similar apps that does this kind of model I described?

This is my idea, but I am wondering if there is some other way to charge for the service?

As previous answer you can do RTM model - your login/password will check if user is premium. Or you can sell another app ( premium key ) that user downloads and your main app will unlock premium features.

I would make the app a free interface to your web site, which also has a premium service, which users, if they purchase, can also use through the App. The key here is that the website service interfaces enforce the restrictions, not the app itself, although you could put some indicator prominently in the app that displays the user's subscription status to the site for example.

Make sure it's not the ONLY interface to your website services to solidify such an argument and it will be difficult to argue that this is payment for the "product distributed via the market" as the product is simply an alternative interface to your web site's services, which aren't free.

Disclaimer: Hire legal advice to look at this plan, and the Marketplace agreement because IANAL.