Google Analytics for SubDomain?

Hi! Guys, Which is best practice to track subdomain and main domain for SEO.

Tracking both domains under single web property in Analytics
Tracking both domains separately using separating Tracking ID

and how to implement it in Squarespace website?

The answer to your first question depends solely upon your requirements.

If your objective is to analyze both the main and sub-domain, then your answer would be, put code in both.

Here is how you insert the code:

Here is how to insert the code:

Hope that helps...