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