They do not. All of their current aids are unlocked last I heard.
From the web …by AI
No, ReSound hearing aids, including those purchased at Costco, are generally not locked to a specific provider and can be programmed by other qualified professionals. While some older Kirkland Signature models (KS5 and KS6) were locked to a specific version of Costco’s software, this practice has been discontinued. Modern ReSound hearing aids, and those sold at Costco from the KS7 onwards, are not locked, and can be programmed using standard ReSound fitting software.