Setting the extra data is covered here: https://wyday.com/limelm/help/extra-data/
To get the extra data, use GetExtraData().
My guess is that you don't actually want to collect this information when your app is run. First of all, we strip out newlines from extra data.
Use custom license fields when your customer purchases your software: https://wyday.com/limelm/help/license-features/