when you ran netinstall, did you accidentally remove the licence key from the screen, where it says "Key:" near to top right thus effectively telling it to remove it? If so, too late now of course, but never do that.
If you give an email to email@example.com
with your software ID, they can send you the correct matching licence key and you can then paste the text you send you back into the running routerboard via telnet or winbox.
Switch it off as it will make even more difficult for you after 24 hours of usage. So if you switch it off after playing with it for 1 hour today, then next week you still have another 23hrs to play! It only counts down with 'uptime' but does not when switched off.