Bitcoin Forum

I singed a transaction yesterday with bitkey setup.

Two Electrum wallets. One watcher only one on another PC cold. https://bitkey.io/

So I have the file on the shuttle USB with the signed transaction. My guess is I can broadcast it any time I want to, even a year later. But I just want to ask to make sure.

Yes. If your inputs are still valid (ie. still unspent and confirmed), then you can still broadcast your signed transaction whenever you like.

Check your receiving address though, you won't be able to retrieve it if you have lost the key or the service has a time-limit for deposits.

Yes you can. The only caveat is that if the fees go up, your (lower fee) transaction might not be included in a block ... or it could take a loooong time. You might have to contact a miner and pay him to include your transaction.

I read about one guy, who had an old signed transaction with a very low fee and he was having problems trying to get it confirmed in December 2017, when fees were very high.... 
He did succeed in the end  :)

Technically, you can, but only if the  nLockTime  (https://en.bitcoin.it/wiki/Timelock) of the transaction has been reached.
If you publish a transaction whose lock time hasn't reached then it will be rejected by nodes on the network and won't make it into a block until that time has reached.

Thanks guys. Well be reading up on the locktime thing later unless anyone will give me a quick and easy version.

So lets assume it gets rejected, then my wallet will show the coins as in never transfered and I just can make another transaction?

nLockTime transactions are non standard and won't be mined until the lock time has elapsed, then it can be propagated by the nodes and then mined.

The bolded is correct.
Anytime you make a transaction, as long as it hasn't been added to a block then it's still "present in your wallet" (although your wallet won't show you) until it has been mined and the ownership transferred to someone else.

yes you can but only drawback is if network is congested and fees goes up then your transaction might stuck in a limbo for some time.

At what point does the transaction get kicked out of the mempool?

What transaction?

There is no "the" mempool; all nodes have their mempool.

However, the default expiry time for a bitcoin node to kick out an unconfirmed transaction from the mempool is 2 weeks, although this can be configured locally by the node operator to either less than or way more than 2 weeks.