I want to publish my application for paid. what are ways to get payment from the user if they install my application ?.
You can use AppExchange Checkout, powered by Stripe, or you can choose your own Merchant Account service, such as PayPal or Authorize.net.
There are a few caveats for using Checkout, though:
The fee to use AppExchange Checkout is 15% plus 30 cents per successful transaction. We don’t charge setup fees, monthly service charges, or card storage fees. There’s also no minimum revenue share.
You can’t accept payments from every country yet. For a list of supported countries, visit https://stripe.com/global. If your country isn’t listed, sign up to be notified when Stripe is available there.
You must distribute your offering as a managed package.
You can’t use AppExchange Checkout with OEM apps.
As long as you don't mind the fees and limitations, this is a rather convenient scenario for you and your clients, since it is integrated with salesforce.com already. You're also free to browse the AppExchange to find another third-party vendor if you choose.