I found the solution myself. Logged off from the trial account. Then, all of a sudden the respective options showed up and I could purchase the stand-alone license.
@mcsilver: Indeed, 1Password shouldn't be trying to sell you a license when you're using a 1Password account, since the membership includes all of the apps. Anyway, glad that you were able to set it up without an account, if that's your preference. Just keep in mind that 1Password is licensed per person, and it may not be someone else's preference, or in their best interest to depend entirely on local data. It could help your loved ones a lot to be part of a 1Password Families membership where they have all their 1Password data backed up automatically offsite, so they can access it even if their devices are lost, stolen, or destroyed; and you could also help them recover their accounts if they get locked out -- in addition to securely sharing vaults without any setup required on their part. Food for thought. Happy holidays!