Is There a Limit to the Number of Subdomains Allowed for a Single Primary Domain?

CookieYes allows consent sharing across a main domain and an unlimited number of subdomains. 

You can display the same banner on all subdomains with a single subscription To enable Subdomain Consent Sharing, subscribe the main domain to a plan and follow this guide. 

If a user provides consent on one of these websites, it will automatically apply as consented across other subdomains as well. If your subdomains use distinct header files, ensure to include the same installation script to display the banner on those pages as well.