So, first I noticed that the key would require multiple attempts to work. Then, I noticed that I needed to be close to the car. And finally, it completely stopped working.
I pulled out the spare set of keys and the same experience. Naturally, I went online to research and one of the explanations I read was that sometimes the key needs to be reprogrammed because the communication between the car and the key is corrupted. No single website gives a decent explanation and when I tried to do it, nothing happened.
More research and I concluded that maybe the battery was dead, not just in the fob that I had been using for about 6 years now, but also in the spare key, which was never used but the battery was old anyway.
What you may want to remember is that if you bring the car to a dealer, you may end up paying a couple of hundred dollars, but if you can do it yourself, it will be less than $5. However, I had never done it before so I was afraid to even try.
Finally, I got the courage to do it and ordered the batteries from Amazon. Please check carefully what battery you will need and it is not a bad idea to open the fob to check it if your manual does not tell you or you cannot find it online.
Then it is time to find a video on YouTube and there are so many of them for nearly all the car models, but even if you cannot find the one precisely for your model, chances are that the basic process is similar.
Replace the battery and for me, it worked right away. I was afraid that because the battery was dead for so long or that I replaced it, I might need to reprogram it, but no, as soon as I pressed it, the key worked. So don't be afraid and just do it -- it will save you a ton of money.