Tool to keep track on session/acc spending

Hey.

So my issue is, that im about to buy an ad account. But the issue is, that the account has an unlimited budget, which means in theory, i could just spend 100K just like that. So atm the seller is looking for a solution, where he can gain me access but still have 100% control of the account/session so there is no way i can just burn and churn.

So the question is, is there any tool/solution for this purpose?