You can change your Systeme’s Subdomain under the Account settings anytime. However, do take note that all published pages whether it is in blogs, funnels, or everywhere under your account will be reflected immediately.
Is it a good practice to change the subdomain (or domain)?
From the Search Engine Optimization (SEO) practice and marketing point of view, changing subdomain is not recommended. Search Engines like Google may already have indexed your page with the subdomain you specified earlier. When you change to a new subdomain, it will not get updated instantly in Google’s cache.
Likewise, your visitors or prospects may have bookmarked and already remembered the link to your pages using the subdomain you used. By changing to a new domain, the old page will be dead and cannot be found.
If you run an advertising campaign (eg Google Ads, Propeller Ads, etc) that directs users to your Systeme’s pages, you want to pause your advertising campaign first.