Electrum (and Bitcoin) addresses do not expire. The payment requests that are made specifically only uses each receiving address once only for better record keeping and privacy. It is perfectly fine to use it for multiple transactions, it'll stay valid.
So I can use it as an address in the signature campaign, right? I was just a confusing since it says "unpaid" so I was thinking after the transaction is done the address is not usable anymore.
I didn't use my electrum wallet for a long time so I didn't know these new updates, last time there was a receiving address that is permanent.
Thanks for your help!
As long as you have your seed phrase (and passphrase if included) or private key to your address, you are good to be using the address for transactions just like using it for signature campaigns on this forums. But, for privacy reasons, it is not good to make use of only one address, so that your whole funds should not be tracked to one address, but their are exceptional cases like using it for signature campaign on this forum in which you have no option, it has nothing to do with your security and the address will always remain valid as long as you have the seed phrase (and passphrase if included) or private key to the address.
All of your addresses can be used forever and for multiple transactions.
You don't even need to set the expiration time to "Never". As stated ranochigo, there is no expiration for a bitcoin address.
The purpose of having expiration time for a bitcoin address in electrum is know whether you have received the fund in time or not.
Let's say I want to sell something to you with bitcoin. I tell you that you must send me bitcoin in 1 hour. Otherwise, I won't accept the transaction
I give you an address and set the expiration time to 1 hour. In this way, electrum will show that whether you have sent the fund before the deadline or not.
I see that how it works!
Thanks for your help!