They do not expire, but they are archived after a certain length of time.
Live accounts with a balance of over USD 5 are archived after five years of inactivity.
Live accounts with a balance of under USD 5 are archived after one year of inactivity.
Any balance remaining on the account after being archived is transferred to a wallet automatically.
Once the account is archived, it cannot be recovered. You will need to open a new live account from within your Backoffice.