There are a few different types of invoices you may see in your SpringboardVR account.
Subscription Fees: This is the invoice you receive every month which covers your monthly SpringboardVR subscription.
Monthly Licensing Fees: This is available on the first of every month and includes the cost of your ppm licenses and any renewed monthly licenses for each title.
License Purchase: This invoice is for when you buy a monthly license in the middle of the month (prorated) or a yearly license. Every time you buy a new license, this invoice will be available immediately in the Invoice History page and sent to your inbox.