This tutorial describes and explains how to setup EDD Order Numbers by Gateway addon, available here.
First time configuration
Go to EDD Settings → Payments → # by Gateway tab.
When you activate the Sequential order by Gateway option you must Save Changes to display the Active Payment Gateways. (A Notice will probably appear to start the re-numbering process, but for now you should ignore it until you have all the options configured).
After Save you can choose the Payment Gateways that you want to be billed and numbered separately from the rest.
The numbering can be carried as an individual unique sequence for each payment gateway. For example, one sequence for Stripe, a different sequence of numbers for PayPal, etc.
Or you can also choose if you want a joint numbering for all of them by selecting the option “Only one Sequential numbers”. When you check this option you must save again to update the form fields for the global numbering.
The difference is that it will be a single numbering sequence for the payment gateways chosen there, ignoring incomplete orders or orders paid with other payment gateways which will continue to maintain the numbering given by EDD.
Each Payment Gateway Order Numbering Sequence consists of a Prefix, the next number to be used and the unique Postfix EDD uses from the Sequential Number Postfix field.
By saving the form we will be able to do the Re-Numbering process of past orders.
The From Date field will be used in the re-numbering process of already saved orders (leave blank if you want to process all orders from the beginning).
How this process is carried out: Setup EDD Order Numbers by Gateway
Next order number value must be 1 in order for that Payment Gateway to be taken into account to process the re-numbering from the date indicated in the From Date field.
When saving Options, if there is not at least one sequence with next order number value 1, the upgrade link that performs the process will not be activated.