<p>Suppose I want to write a membership payment app. In this program, I want to give an address and members should send their membership fee to this address:</p>
<ul>
<li>How can members prove that they paid the fee ?</li>
<li>What do I have to get from members to prove it?</li>
<li>how app should check and verify the owner of transaction ?</li>
</ul>
<p>I know there is software for this, but I want to know how this system works.</p>

CC BY-SA 4.0
2020-12-19T20:58:46.303Z
i don't want use different address for each membership transaction.
bitquest
CC BY-SA 4.0
2020-12-19T21:00:00.640Z
you still should
Pieter Wuille
CC BY-SA 4.0
2020-12-19T21:03:51.140Z
let me describe a scenario : I get 1btc from  user-A  to address-A and 2btc from user-B to address-B now app have 3btc and app want send 3btc to another address , how it is possible to send 3btc from 2 different addresses in one transaction ?
bitquest
CC BY-SA 4.0
2020-12-19T21:19:41.957Z
Transactions don't really have a "from" address. They have inputs, which spend outputs created by previous transactions. It doesn't matter what addresses those outputs were sent to. Think of it as melding and reforging coins.
Pieter Wuille
CC BY-SA 4.0
2020-12-19T22:41:02.437Z
with a single private key can I provide many addresses to users ? or I should make private key for each addresses ?
bitquest
CC BY-SA 4.0
2020-12-19T22:43:02.850Z
Every key corresponds to one address. Wallet software will do all of this for you.
Pieter Wuille
<bitcoin-core><transactions>
how make an membership app
bitquest
# how make an membership app

(Asked by: username_0 on 2020-12-19)

Suppose I want to write a membership payment app. In this program, I want to give an address and members should send their membership fee to this address:

* How can members prove that they paid the fee ?
* What do I have to get from members to prove it?
* how app should check and verify the owner of transaction ?

I know there is software for this, but I want to know how this system works.

**Tags:** bitcoin-core, transactions

> **Comments:**
> **username_0**: i don't want use different address for each membership transaction.  
> **username_1**: you still should  
> **username_0**: let me describe a scenario : I get 1btc from  user-A  to address-A and 2btc from user-B to address-B now app have 3btc and app want send 3btc to another address , how it is possible to send 3btc from 2 different addresses in one transaction ?  
> **username_1**: Transactions don't really have a "from" address. They have inputs, which spend outputs created by previous transactions. It doesn't matter what addresses those outputs were sent to. Think of it as melding and reforging coins.  
> **username_0**: with a single private key can I provide many addresses to users ? or I should make private key for each addresses ?  
> **username_1**: Every key corresponds to one address. Wallet software will do all of this for you.  

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## 0 answers

