If you login ai.nero.com with Nero account A to purchase products with PayPal
Step 1: Choose PayPal payment to place order
Step 2: Billing details page
Step 3: Pay with paypal
Step2 determines which account the Day pass credits will be placed in
1. If you keep the default account A, then go to step3, the credits you purchased will be in account A
2. If you change the email address to another account, e.g account B(can be paypal account or other account), then go to step3, the credits you purchased will be in account B. At this time, you need to login with account B in ai.nero.com to get the credits.