Many Android users have expressed alarm that Android Location Services have to be turned on for the Purpl PRO App to function. The reason for this is that the Bluetooth libraries the App uses are lumped in with location services. Purpl does not use or save any location information.
Apple users do not need to have location services enabled to use the Bluetooth connection because of the different way Apple organizes the hardware libraries within their ecosystem.
Users that are particularly concerned with this issue can purchase an iPhone or other iOS device. At Purpl, we use the iPhone 7s+ for internal testing, which can be obtained at online and local retailers at a reasonable price.
Our servers do save some information. This is primarily spectral data and which is tagged by device serial number and user-provided email address. Users can also save measurement results to their Portal by pressing "save" on the Results screen in the App.