Is paying a monthly sum to a gold shop for one year, and buying gold with the paid amount plus the value of an additional month from the shop at the end of the period, considered permissible or usury?

It is not permissible to collect monthly installments for the purchase of gold if the money remains with the seller and he benefits from it, and then gives the buyer an increase, because this is considered a loan that brings benefit to the lender (the buyer), which is usury (riba) forbidden by Islamic law.