I was surprised to see jOOQ went comercial. Still is open-source, though. The paid versions apparently just include direct support, warranty and work out-of-box with Big Corp databases.
What is wrong with paying for software? It's very reasonable license too. Cost-free for open source databases and without immediate support. This is classic Free Software licensing.
Although, unlike us, Typesafe is completely intransparent with respect to pricing both for licensing and support subscriptions. Have you asked how much it will cost to go to production with Slick and Oracle database? You will be in for a surprise!
With jOOQ's transparent licensing strategy there are no strings attached.