Music 1 should not be left running. If you are not working with it, close it out. Have the auto-shutdown enabled, as well. The reasons for this are twofold. First, M1 makes a backup of your library database each day. If it is left running for many days and you then find yourself in need of a restored copy of your m1 library from a day or two ago, there won't be one and you'll have to restore back to an even earlier time than you'd prefer.
Second and most importantly, if Music 1 is not properly closed, it will ask for a re-activation code the next time you go to load it. This is because the last thing M1 does when you close it is to re-set an internal flag saying "this is a licensed database." If M1 is running and Windows does a re-start, it will not properly close M1 before it does, the internal flag won't be set and you'll be asked for re-activation the next time you start it. This can also happen if M1 is running and the computer loses power.