What is the legal ruling regarding life insurance policies from which the beneficiary receives monthly installments and, at the end of the term, recovers the total of the installments along with unspecified pre-determined profits?

Life insurance contracts are not permissible in Islamic law. It is a type of forbidden commercial insurance. The contract must be rescinded, with each party taking what they paid, along with repentance for entering into this forbidden contract. The lack of a specified interest rate is irrelevant, as the contract itself is fundamentally void.