I'm afraid you can't. Even if you buy PictureNFTizer Multi-Chain 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 Multi-Chain is an Upgrade or Up-sell which adds the Multi-Chain features in your PictureNFTizer account.
3. Since PictureNFTizer Multi-Chain 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 Multi-Chain in your account.