Design OK, Terms are a deal-breaker
The Terms of Service are a little out of balance. I know it's all the rage now to advertise super-fierce terms, but business realities need to be considered.
"suspend account after 4 days" and "delete all data after 30 days" is far too harsh.
Choose to review a potential client at the start if you need to, but be able to deal with up to a 30-day lag on invoices. The only exception I have ever heard of is food produce wholesalers, who have data that cannot have value after such a 4-day period. Data essentially lasts forever.
Your terms would lead to situations like "Oh, Darby in Accounts payable took the day after Thanksgiving off, so that invoice from Tuesday didn't get paid until the following Monday." (And that's a best case scenario!)