In Office 365, the default password expiration policy for all of your user accounts is 90 days unless you configure a different password expiration policy. For Lync Room Systems accounts, you can select the Password never expires setting with the following steps.
PS C:\Windows\system32> $cred=Get-Credential admin@$org
PS C:\Windows\system32> Connect-MsolService -Credential $cred
PS C:\Windows\system32> Set-MsolUser -UserPrincipalName confrm1@skypelrs.onmicrosoft.com -PasswordNeverExpires $true
For more information, see the Lync Online Power Shell documentation at http://technet.microsoft.com/en-us/library/dn362831.aspx.