How to sell software license keys?

[mayerpeter]

How can I sell software license keys and monthly subscriptions with Spree? At the moment I am using Sendowl (see https://www.sendowl.com/demo) which provides such functions. With https://github.com/spree-contrib/spree_digital I did not find a solution. Would love to change to spree if it would offer such features for digital delivery with software license keys and monthly subscriptions.