Hi Gabriel,
At this time, Cloudability and Apptio BI are not able to accept data ingestion from Datalink. Apptio BI can only ingest data from one of the Apptio products (eg. Cloudability).
If the cost is already coming into Cloudability you could utilized the Calculated Metric feature in Apptio BI to make the calculations you want. The Session Count would have to be a static number in this scenario though, and if it changes, you'd need to update the Calculated Metric.