App Store keeps asking for a payment method

If you want to make purchases or update / download apps, including free apps, you need to have a payment method on file.

If you don't have a credit card or don't want to use a credit card, you can also use your Apple ID balance as payment method, see -> Add money to your Apple ID balance

Add money to your Apple ID balance – Apple Support (UK)

See also: 

What you can buy with your Apple Gift Card or Apple ID balance

What you can buy with your Apple Gift Card or Apple Account balance – Apple Support (UK)

How to redeem your Apple Gift Card or App Store & iTunes gift card

How to redeem your Apple Gift Card or App Store & iTunes gift card – Apple Support (UK)

When redeeming a gift card, (1) the amount will be credited to your Apple ID balance and (2) then you need to set your Apple ID balance as your default payment.

(1) See -> Check your Apple ID balance

Check your Apple ID balance – Apple Support (UK)

(2) See -> Add a payment method to your Apple ID

Add a payment method to your Apple ID – Apple Support (UK)

If you update your payment method or add funds to your Apple ID balance, It would take about 1 to 3 business days in order to process.

If you're still unable to update your payment method, Contact Apple Support.

Also read the articles below ⤵️

If you can't redeem your Apple Gift Card or App Store & iTunes Gift Card

If you can't redeem your Apple Gift Card or App Store & iTunes Gift Card - Apple Support

• You can't redeem Apple Gift Cards or App Store & iTunes Gift Cards outside the country or region of purchase. For example, if you bought an App Store & iTunes Gift Card in France, you can't redeem it in the App Store in the United States.

About Gift Card Scams -> About Gift Card Scams - Official Apple Support

If you update your payment method or add funds to your Apple ID balance, It would take about 1 to 3 business days in order to process.

If you're still unable to update your payment method, Contact Apple Support.

You can download free apps, but you need to have a payment method on file, even if the app you want to download is free.

As long as you only download free apps, it costs nothing.

Then your payment method remains intact.

If you are going to download a free app, there is a possibility to purchase the 'better' version, for example from a free version to pro version.

But that is not mandatory.

However, with the free version there is an advertisement.

Use your Apple ID balance as default payment, then it is up to you whether you use it or not.

Free apps has also In-app pruchase.

Your payment method is actually a kind of deposit, if you buy something, it will be charged.

For example this is an free app, with Offers In-App Purchases.

Scoll down and you will see:

As long as you do not take out a trial period or a subscription, the app will remain free.

If you take a trial period or a subscription, you have to keep an eye on it yourself.