An active Apple Developer account membership is required in order to publish app updates and keep the app live on the App Store.
The cost of the Apple Developer account membership is £79 per year and it is a responsibility and cost of the business owner to pay and upkeep this.
During the sign up process, you can opt in to have your membership automatically renewed by selecting the Auto-Renew Membership checkbox in the Membership section of your account. If you have opted in to automatic renewal, the default credit/debit card associated with your Apple ID will be charged the annual membership fee on your expiration date.
Manual Renewal
Alternatively, you can renew manually starting 30 days before the expiration date of your existing membership or any time after it expires. Your expiration date is available in your account on the developer website.
To renew, sign in to your account and click the "Renew Membership" button. If your membership is still active when you renew, your new membership will activate as soon as your current membership expires.
If your membership has already expired when you renew, your renewal will activate once you complete the renewal process and any free apps you had available for download will become available again within 24 hours.
If your Apple Developer Program membership expires, your apps will no longer be available for download and you will not be able to submit new apps or updates
Apple Support
For further information please see the Apple Support page:Program Renewal - Support - Apple Developer