There are two in-app purchases available to enable unlimited recording time:
Unlimited Recording on a Single device (for purchase or free with compatible hardware): when this in-app purchase is completed, you have unlimited recording time (based on available device memory) on a single device. It’s still possible to connect Satellites, but the Satellites’ recording time is limited to 60 seconds. Unlimited Recording on a Single device is unlocked at no cost by connecting compatible Apogee or Sennheiser audio hardware. See this article.
Unlimited Recording on Multi-device systems (for purchase, and lower cost if already upgraded to Unlimited Single): when this in-app purchase is completed, you have unlimited recording time (based on available device memory) on a multi-device Master. The in-app purchase may be downloaded to any other devices that share the same Apple ID at no extra cost - when these devices are configured as Satellites, they have unlimited recording time as well.