Power BI Desktop and large data volume

There's a fixed limit of 1 million rows placed on the number of rows that can be returned in any single query to the underlying source. This limit generally has no practical implications, and visuals themselves aren't going to display that many points. However, the limit can occur in cases where Power BI isn't fully optimizing the queries sent, and there's some intermediate result being requested that exceeds the limit. It can also occur while building a visual, on the path to a more reasonable final state.

Before looking at Premium I would try to figure out why in the world you're returning queries with that many rows (a visual typically doesn't require more than a few hundred data points). Something is likely wrong with the query optimization if it needs that many rows from a query.