How long before transaction is removed from the Mempool

Question

So I have a transaction T1 that has been stuck in pending because I put the gas really low.

I forgot about this and then tried to process two transactions after with $126 gas fee and $111 gas fee.

I understand these won't be picked up until the pending one with a lower nonce is processed. But now I don't want to process those two that come after because then I will lose $240 in gas fees.

My current thought is to just submit a new lower nonce transaction with zero fee to stop the two expensive ones from getting picked up until they are cleared from the mempool. Is this my only option?

What my Etherscan looks like

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[T3] [1 hrs ago] [pending] ($126 dollars)

[T2] [1 hrs ago] [pending] ($111 dollars)

[T1] [16 hrs ago] [pending]. (5 cent gas fee)

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From my understanding if the cheap ones purged, the other ones will get picked up beacuse the fee is high, and since its sold old it will fail, and I will lose my gas fee. So I was thinking of always trying to maintain a cheap one with lower nonce until the expensive ones are purged..

Answer 1

Your valid signed tx expires - it's removed/purged from the memory pool - only if it becomes invalid.

To become invalid, another tx with the same nonce should be mined, or the account should not have enough funds to pay for that tx.

To mine a tx replacing another tx with the same nonce, you need to increase the gas price.

There's no way to do exactly what you are asking for, that is, paying lower gas fees for T2 or T3, but you can obtain a similar result.

Send a new tx that transfer all your funds to another account, use the same nonce of T1, and set a decent gas price (base fee is 39 Gwei now, ~1,40$ for a transfer, pretty honest). The tx will be mined, and your T2 and T3 will be purged because they cannot be satisfied anymore.

For completeness, there's another workaround (a more complex one, it depends on your social network ^^): contact a miner that is interested in inserting your replacing txs for 0 gas price and get paid off-chain for the service.

If you don't need the original EOA to be preserved (i.e., you use it to be identified in some smart contracts, some ÐApps, etc.), I think the first option is the easiest and fastest path to follow.