Howdy Luna
If your using veg tan leather , after the tooling or molding , some type of oil needs to be put onto the leather. Over the years neatsfoot oil has been used. I've used neatsfoot oil, olive oil, and have been told by others here they have used vegetable oil and even butter; the oil is a natural lubricant and preservative. Lexol, is a blend of ingredients that is typically used on chrome tan leathers ie upholstery type leathers. Lexol interacts with the leather and the chemical process, and does a very good job.
I currently use a product called Bee Natural Saddle oil on my veg-tan projects after I've finished my tooling.
Just a reminder, a little bit goes a long way.
Happy leather work
Tim