It is very important!!!(overuse of ! i know, but it is one important step).
You have to trust eachother.
When you reached halfway up with your project and one anonym greedy ******* is stealing code, or selling retextured meshes, perhaps you change the way you think…
I hold it so:
Make a picture of your ID card, black out the numbers, but adress name and country has to stay intact.
Then make a selfie, where you hold up a piece of paper with some special written words under your face (for project xyz).