As long as you no one has seen nothing happen further! Theft is usually punishable with a Verwahnung!
Tell me please times in which the shop has happened? Then I can help you better!
Because you are over 14 you can be held accountable for full consequence, in case of recurrence juvenile detention.
Let it be in the future.
No matter what others say or do if you are caught you coming into the company archives. Eventually there will be no warning. Every policeman can see what you've been up to.
If you no one has seen, nothing. If they approach you, it is an attempted theft with escape. It depends on the judge or prosecutor, as you "punished" will. But you will be punished then in any case. I guess fine or a few hours of community service. But it will not be overly harsh punishment because it was your first time and you're not a criminal
Have you been caught or seen it?