Each SIM stays active for 30 days, if you don't top up within this time the SIM will expire. This means, you will not be able to make any calls except for emergency numbers. If your SIM expires, any remaining credit on the account will remain in your account, all you need to do is to top up your account and number will be active again.
If you want to check your SIM expiry details you can dial *124# at any time.
If you want to check the credit balance on your SIM dial *120# or visit My Digicel App by click here.