Do we require a separate Semantria account for each dataset that we are assigning sentiment for?
No, with Semantria a user only needs one account and can work with multiple different datasets. By creating different profiles (aka "configurations" for API users), a user can assign certain parameters to specific datasets. For the Semantria API a customer profile comprises of a set of configurations, which specify the categories, blacklists, queries, entities, and sentiment-bearing phrases that apply to a given dataset. A profile can be applied on demand to different datasets, or be specific to an individual dataset.
For example, when using the API you need to analyze data for company A and company B each will have their own profile even if their configuration settings are the same. In this way, the different profiles distinguish the data for company A from the data of company B.