2. Is there a limitation of users fo the HygroLab

The HygroLab operating system has factual no user limitation.

The only limiting factor is the internal memory space of 16 GB. If the memory gets full there will be no possibility to either make a measurement nor to set up a new user. Please make sure to regulatory transfer the measurement documents externally and delete documents to make sure that there is always sufficient memory capacity in the HygroLab.