Private key for applications signing

I have an application that I want to publish to the Google Play Marketplace and make it paid. To do this I must sign it with private key from the market. I've also heard that I can also do this with the help of self generated key.

The problem is that the market key has big expiration date and I want to use the license for only one year. After that time the user must paid for and re-download the app again.

Can I sign my application with my own private key and then use licensing serv开发者_开发百科ice for check expiration date?

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Yes, that's possible. Take a look at Application Licensing for more details. (But your signing key will still have to last for years because "If you plan to publish your application(s) on Android Market, the key you use to sign the application(s) must have a validity period ending after 22 October 2033."*)