This is serious, as there are some wallet addresses that EXPIRE after a certain number of hours, if the trx does not go through, BTC could be lost forever...
...
BTC won't be lost forever.
Some third party services, merchants or even people like you and me using a wallet like Electrum can set an expiry date for a payment request. An example of a use case could be to prevent customers from submitting payments after the quoted price is no longer valid.
That's why your bitcoins won't be lost and wallet addresses don't expire. In case you send bitcoins to a third party service like kraken or you use a payment gateway like coinbase, you'll have to follow its rules and this is not bitcoin's 'fault'.
Coinbase example:
If a customer pays a merchant after the 15 minute window has closed, a few things happen:
Coinbase forwards the funds to the merchant's wallet along with a note explaining that the payment was late.
Coinbase sends an email to the merchant to notify them about the incoming transaction.
another example w/ bitpay
other companies will ask you to send them a support ticket as they'll take care of it. But again, this is just their police to protect their customers from aggressive price fluctuations, not because addresses really expire. Their expiration date is just the duration they accept for a payment to be made. If you send bitcoins to an 'expired address', that address will contain the amount that you sent, bitcoins don't disappear from nowhere