Rekordbox DJ activated, but still asks for a license key every time

Greetings,

One of my students purchased a license key for Rekordbox DJ. We activated the software successfully. However, when she starts a new session (after restarting her computer), it asks for her license key again. This is happening every time she uses the software.

It should only need to be activated once. Is there any way to keep the software activated?

Her setup up is the following:
Macbook Pro 13" i5
OSX 10.10.5 (Yosemite)
DDJ SR