There are couple scenarios that can happen depending on what you do:
- If you are logged into your account, no matter what device you buy it on, it will be attached to your account
- If you purchase something and provide the email address that is on your account, the you will be prompted to log in and attach it to your account
- Otherwise, the purchase is attached to the email address you provide, and you are prompted to either log into an existing account or create a new account to connect that purchase to an account