I am very familiar with your country and my advise to open a Domiciliary US Dollar account or having a friend pay from abroad from their international account are your best options.
Nigerian visa and mastercards that are associated with the local bank’s Domiciliary US Dollar account can easily cover the Manager subscription as the lowest limit is US$1,000 with many (depending how much funds in the account) will allow up to US$10,000 card transactions compared to the US$20 with the Naira cards without CBN restrictions. Many Nigerian banks now even stopped allowing any FOREX on domestic Naira card transactions see for example https://punchng.com/more-banks-suspend-international-transactions-on-naira-cards/ .
Please note that there is no need to keep repeating the same request across the forum. The answer above should suffice for you to weigh your payment options. This is the reason @Tut closed your repeated request some hours ago Unable to make payment for manager subscription - #4