WinRT Universal app - Licenses

Hi,
I'm very confused about licenses.
I'm developing Universal app (Windows 8.1, Windows Phone 8.1) and not sure which library should we use?
Probably:
WP 8.1 - WP8_15 library (pdfviewer_wp8_1.5.zip
W8 - pdfviewer_w8_1.5.zip

Can i use demo license just for test features and check if all working as expected? How? I don't know how t acitavte license on Windows Phone 8.1 project.
NOTE: There is difference betweer WP8.1 Silverlight and WP8.1 Universal app
Thanks for info,

demo project default actived a license, binding to demo product ID.
and you can copy product ID and active codes to your demo APP.