Here’s and extremely simple script to remove the subscription warning box from Proxmox. Proxmox is Open Source and the subscription notice is just to try and get themselves some money by providing support for customers and they really deserve it! The software is free to use at all levels, even commercially but if you require support you will need to pay some money which is fair enough in my eyes.
That said, we can remove the subscription notice without any consequences and it is all allowed. Proxmox even provide instructions themselves.