Bank connection consents last for 180 days for eligible banks. You will also be able to sync bank transactions up to 180 days back in time when connecting sources to budgets. If your bank does not support 180 day consents or 180 day transaction history, new connections will default to 90 days.
After a consent has expired, you will have to renew it to keep syncing transactions. You will receive two emails from Synci some days before consents expire, with instructions on how to renew them.