If privacy is a concern, pick up a pre-paid card at WalMart, a grocery or convenience store. You can use them at Stripe for a one-month, montly renewing, or yearly subscription. Many come already loaded with various amounts from 5 to 100 bucks. Some don't and you just take the card to the cashier or service desk and load cash on it. You can use the pre-paid gift-card style card once then throw it away. Or you can get a reloadable and use it just like a credit/debit card online or in person and then reload it. Reloading it with cash continues the anonymity.

A good online anonymous payment method is Privacy.com

Another anonymous online payment method is BLUR

Your credit card likely has an anonymous service as well, called Virtual Card or something similar. You log in and set up another card number which you can use online. This new number is linked to your card, and you can request that purchases with the new number do not show up on your usual statement and that you not recieve paper mail statements. The way it works varies depending on your bank and card provider.