Fumbling for keys in the dark ends the day you install a smart deadbolt and a video doorbell. You can check who is at the door from the couch, let family in remotely, and stop hiding spare keys under the mat. The physical install takes less than an hour per door, and you will wonder why you did not do it years ago.
Late winter is the best time to catch hardware bundle deals and hire a locksmith or handyman before spring remodeling season hits. Always get at least two quotes for the installation work if you are not doing it yourself, because prices swing wildly between local pros.
That 18-month window is a hard deadline, not free money, so make sure the balance is zero before it ends or regular interest kicks in on what is left.