I'm afraid you can't. Even if you buy PictureNFTizer PRO without the Standard Version, you will not be able to login.
Here is why:
1. PictureNFTizer Standard is the main product which is either a Monthly, Yearly or One Time Subscription.
2. PictureNFTizer PRO is an Upgrade or Up-sell which adds the PRO features in your PictureNFTizer account.
3. Since PictureNFTizer PRO is not independent, you will need to subscribe for the main product PictureNFTizer Monthly, Yearly or One Time subscription first. Else you can't login with only PictureNFTizer PRO in your account.