Enabling no-subscription repositories

On Debian v13 (trixie) 
 mv /etc/apt/sources.list.d/pve-enterprise.sources /root
 
 Create new file 
 nano /etc/apt/sources.list.d/pve-no-subscription.list 
 
 repos 
 deb http://download.proxmox.com/debian/pve trixie pve-no-subscription
 
 Adjust Debian repos 
 nano /etc/apt/sources.list.d/debian.sources 
 
 repos 
 Types: deb
URIs: http://deb.debian.org/debian
Suites: trixie trixie-updates
Components: main contrib non-free-firmware
Signed-By: /usr/share/keyrings/debian-archive-keyring.gpg

Types: deb
URIs: http://security.debian.org/debian-security
Suites: trixie-security
Components: main contrib non-free-firmware
Signed-By: /usr/share/keyrings/debian-archive-keyring.gpg
 
 Verify repositories declaration 
 apt policy
 
 
 Do APT update 
 apt update
 
 
 List packages ready for update, most important that there are new packages from PVE repo. 
 apt list --upgradable
 
 
 Perform upgrade (when needed) 
 apt upgrade