Section 106. A foreign company of the class designated in the preceding section shall not be admitted and authorized to transact business in the commonwealth until, besides complying with sections one hundred and fifty-one and one hundred and fifty-five, it has satisfied the commissioner that it has made a deposit with the state treasurer or with the proper board or officer of some other state of the United States, in exclusive trust for the benefit and security of all its policyholders in the United States including obligees of bonds executed by such company as surety, of an amount not less than one hundred thousand dollars. Such deposit, if made in this commonwealth, may be made in the securities and subject to the limitations specified in sections sixty-three and sixty-six, or in cash or in such other securities as the commissioner may approve, provided that bonds need not be accepted by the state treasurer unless in registered form and of denominations satisfactory to him, and shall not be returned to the company until it has ceased to transact business in the commonwealth nor until the commissioner is satisfied that the company is under no obligation to such policyholders or obligees in the commonwealth or in any other state of the United States for whose benefit such deposit was made, nor until he has given his written consent to such return; provided, that the commissioner may, in any case, authorize in writing the return to the company of any excess of any deposit made under this section over the amount required thereby, if he is satisfied that such return will not be prejudicial to the interests of such policyholders or obligees.