Hi Roman
Yep, it is the same as in ZigBee. In order to deliver in the market Thread compliant devices you need to be member of the Thread Group (affiliate membership cost is 2500$) and pass the certifcation (validation includes: Commissioning, Network functionality and interoperability, Device operation in network) through UL Laboraties.
As start-up company I suggest you to have a look and apply for the Innovation Enabler Program that may(if approved) give you a free membership/certification. You can find all the details HERE.
Hope this helps,
Antonio