For the taxation purposes, the subscription should charge the customer at the last business day of every month. Is there a way to do that instead of charging the customer every month/week?
In the docs https://developer.paypal.com/docs/subscriptions/integrate/ I have not found any way to implement that.
Subscriptions bill on calendar days, and have no knowledge of business days.
Other non-Subscription PayPal integrations, such as using reference transactions or vault, are capable of billing arbitrary amounts at arbitrary times when you do an API operation with the token. (They require the reference transaction feature which is not enabled on live accounts by default, the account owner must contact PayPal's business support --not technical support-- to request it and only then can PayPal guide you on which API to integrate)