1:1 Coaching clients
1:1 Consulting clients
1:1 Done for you services clients
Any group program where you offer 1:1 access in the form of hotseats, voxer, slack, or other messaging systems.
Take for example a funnel builder. If you are using the spreadsheets to calculate your client's potential revenue, that's still considered individual use since the spreadsheet lives in YOUR Google drive and is being used for you to become a better provider.
When and if you want to share the sheet with the client (so it goes in their drive), then you need a group license.