If funding becomes low in your account, you will receive an email notification that your seat has been deactivated. Your balance is lower than the estimated daily spend so the platform switches your campaigns to ‘Inactive’ because it does not want you to spend more than the budget you have allocated to your seat. 

The platform pauses the campaigns on the account until either a budget is added that is more than the daily spend or the daily spend is lowered so it is less than the budget in your account. To reactivate your account, either add funds to your account or adjust the Lines to spend less.