In Proxmox pve 5.2-5 (and Proxmox 6.x) the location of the file that renders the subscription notification has changed.
It is now '/usr/share/javascript/proxmox-widget-toolkit/proxmoxlib.js'
To disable the message locate the line
" if (data.status !== 'Active') { "
and comment it out, then add the line
" if (false) { "
directly below the one you just commented out.
The section will look like this
var data = response.result.data;
//if (data.status !== 'Active') {
if (false) {
Ext.Msg.show({
title: gettext('No valid subscription'),
This will not magically give you a full subscription, but it will stop the message popping up