I don’t really need the block tracking functionality that comes with a licence, but is there any way I can contribute to the project either financially or materially?
UrBackup has really helped me back up PCs on my home network.
I didn’t really need the CBL client yet either, but I do believe purchasing the license puts money in the dev’s hands…hence why I did it 
On your backup server click the “About” link on the bottom right. There’s a paypal button to donate there. Here’s where the link takes you: https://www.paypal.com/cgi-bin/webscr