The A/B testing package is a free package, there's no cost to install it within a CMS or Commerce solution.
I don't believe there's any out of the box connection for A/B testing to Google Analytics but you could create custom KPI criteria if you want to pull things via analytics. There's also this blog article https://world.optimizely.com/blogs/sanjay-katiyar/dates/2020/3/episerver-ab-testing-and-visitor-group-personalization-metadata-into-an-analytics-payload-for-consumption-with-the-google-analytics/ for pushing the payloads to analytics
I have two question about AB Testing
I had license for cms and commerce but if i use Episerver AB Testing. Do i need purchase more license to use Episerver AB Testing?
How can i linked to my Google Analytics property?