2. if there are other serious or recurring irregularities concerning compliance with the conditions for the use of numbering resources referred to in Article 68 of this Act and laid down in the decision allocating numbering resources, unless these irregularities have been removed by more lenient measures in a supervisory procedure. Article 73 (cessation of validity of a decision allocating numbering resources) (1) A decision allocating numbering resources shall cease to be valid: 1. at the proposal of the beneficiary of the decision allocating numbering resources; 2. if the beneficiary of the decision allocating numbering resources ceases to exist; 3. upon revocation of the decision allocating numbering resources. (2) In the cases referred to in points 1 and 2 of the preceding paragraph, the Agency must issue a declaratory decision. Article 74 (fees for the use of numbering resources) (1) Beneficiaries of a decision allocating numbering resources shall be liable to pay an annual fee to the Agency for the use of the numbering resources allocated to them. This fee shall cover the costs incurred by the Agency in the management and supervision of numbering resources. (2) The Agency shall prescribe the method of calculating the fee due to it under this Article by means of a general act. The amount of the fee shall be dependent on the quantity, length and types of numbering resources, and may not restrict competition or create barriers to market entry. (3) The amount of the fees referred to in the first and second paragraphs of this Article shall be set by the Agency using a tariff, with due regard to the necessity to cover the costs referred to in the first paragraph of this Article and with mutatis mutandis application of the fifth, sixth and seventh paragraphs of Article 6 of this Act. (4) Article 7 shall be applied to the charging and payment of fees for the use of numbering resources. (5) Without prejudice to the provision of the fourth paragraph of Article 7 of this Act, the beneficiary whose right to use numbering resources has ceased as a result of the expiry of the period for which it was allocated or through no fault of its own shall pay the fee on the basis of the number of months for which the right was valid, but not less than one-twelfth of the annual fee (6) Without prejudice to the provisions of the first paragraph of this Article, an undertaking shall not be required to pay the Agency for the use of numbers transferred to another undertaking. The undertaking to which the numbers have been allocated shall be liable to pay the Agency for these numbers. The Agency shall take into account the information sent by the undertaking in accordance with the ninth paragraph of Article 131 of this Act. (7) Payment of a fee for the efficient use of a limited natural resource in order to ensure the optimal use of numbering resources shall be required for numbering resources allocated on the basis of a public invitation to tender, unless the numbering resources are required for performance of activities in the public interest in accordance with the first paragraph of Article 66 of this Act. This shall be a revenue of the state budget. The minimum amount of this fee and the method of its payment shall in this case be set in the decision on the initiation of a public invitation to tender procedure. In deciding on the public invitation to tender criteria and the minimum amount of the fee, and setting the method of its payment, due