Membership approval

Hello
I sell ebooks and use WP Members to restrict access to video pages linked from the ebooks.

What’s the best way to confirm a new member registration based on a purchase?

So, a customer buys an ebook and is prompted to create a user account via WP Members.

I’ve been approving them manually, one at a time.

How can I automate new member approval based on their purchase?

Do I need a product like Easy Digital Downloads? Some other service?

TIA for any suggestions.

Thanks for a great plugin.