Report on users who have not logged in within the last 90 days

Hi Trevor - the Gainsight 360 report should allow you to see this information.

We looked through this, both myself and Gainsight Support, and the closest we can get is listing everyone who has logged on the comparing that to the complete list of licenses, then those who aren't on the list haven't logged in. Are we missing something?

Yes, that's correct, you'll have to do a comparison with the data from the Gainsight 360 and your license list. 

The way that license assignment works in SFDC is that you as the admin have visibility into which accounts have licenses provisioned, but Gainsight does not (SFDC provides us stats on aggregate numbers but not on current users individually). We are able to identify users via usage data, which is available in the Gainsight 360, but if a user has no page activity we aren't able to know if this is because A) they have a license and they aren't using it or 😎 they no longer have a license provisioned. 

This is why you'd have to compare the two lists, but the Gainsight 360 report will be able to show you active users. 

Hope this helps.