Pretty much the title. I can't seem to figure out how to stop this monthly payment.
Isn't that a Microsoft Product? Wouldn't you need to ask them?
Unless you actually meant the VEGAS Pro 365 monthly subscription.
"Subscription and cancellation conditions: VEGAS Pro 365 will be available immediately after payment and activation. The charge for the minimum term is payable as a single sum upon conclusion of the contract. The minimum term begins on the date of purchase. If you cancel your order within 14 days, you will receive a complete refund. The contractual period of VEGAS Pro 365 will be automatically extended by one month at a time until you cancel the agreement You will be informed well in advance if the extension rate or taxes included change. A cancellation is possible up to 1 day before the end of the contract period. To cancel the contract, please send an email stating your customer number to: infoservice@magix.net"'
(From "Purchasing details" below a 1 month payment plan option at https://www.vegascreativesoftware.com/us/vegas-pro-365/ )
Choose your personal payment plan there and click the relevant Purchase details that apply to your plan.