What do I do? Leaving apartment for winter months

I moved into a studio located in Tempe, AZ, and in August, I worked with the landlord to schedule pest control. It seemed to have worked for the most part. Just today, though, I think a larger German roach fell out of my grocery bags. I am almost sure it did, because it quite literally appeared on the floor out of nowhere, even though I had just been looking at the floor, lol. Last sightings were small nymphs, I suspect, that came out of the kitchen sink drain on nov 20th and 18th, but I quickly killed them. Just two on each day. Arizona had a bad rainy season then. For all of October, they disappeared. Completely gone. Now I’m wondering what I should do? Do I put another batch of Advion gel? Even if there really isn’t anything I’m seeing? I’m going away for a month or so to my parents' house, so I plan to cover the drains. Also, know I am very clean and organized. Extremely particular, to the point where I’m drying out any water sources, too. There are no signs of a wild infestation. I don’t want to see them anymore. /: