Once you have purchased this we will install the ability for you to be able to use this tool. After we have gone ahead and done so, you may activate this based on membership level. 

To add this as a feature for a membership level, simply navigate to Finance >> Manage Products, click on "Edit Settings" for the membership level you would like to activate it for, click on the "Post Publishing" tab, and then check the boxes for the Sub Accounts feature:

You can also limit the number of sub accounts members can have by toggling the "Max Limit" number here:

To find out more about what the feature has to offer, please see the Q&A: Sub Accounts article here. 

If you have any other questions, please submit a new ticket here.