This plugin has a big problem. When the user send the invitation, the plugin save the record in the database, can't be deleted!. For example, if the user send 1.000 invitations, the plugin save 1000 entries in the database, and the user can't remove the own records from the account.
What happen if 500 users, sends 1,000 invitations? 500,000 entries saved in the database!
If you don't want increase the Database Size, don't use this plugin!.
The DB Saves have to be done for tracking purposes. If we dont do that you will lose all invite tracking capabilities. We have however provided a database purge feature in an upcoming release to purge it periodically..