Unbounce:
Next, navigate to your landing page within the Classic Builder. Click the "JavaScript" button located in the bottom left corner of the Classic Builder interface.

An empty dialog box will appear; this is where you can paste or type in your custom JavaScript:
Name your script using the Script Name field.
You’ll want to choose the Placement of the script; this will depend on the script’s functionality or any instructions provided by the third-party app you’re copying this script from, as the placement may differ. Here are the different placement options in the Classic Builder:
Tracking domain and subdomains:
When it comes to tracking your domain and subdomains, you have several options. You can opt to track both the main domain and its subdomains using a single tracking script, which will consolidate all traffic data into one workspace. Alternatively, you can create separate workspaces for each domain and subdomain, depending on how your services are structured.