Where can I get an RFID sticker for my car near Olongapo…

Check this out: https://www.expressway.ph/rfid/installation-sites

What do you use that for? I'm curious whether I need it too.

The closest place I found was in Angeles, and the highway to Manila is cut off from there. Also, be sure to ask whether it works on all expressways before you get it installed. My husband got one in Batangas last week and it was only for the southern tolls. It was pretty annoying. The one I got in Pampanga works on all the expressways. But if you only get one for the northern tolls, it's a hassle, so be sure to ask before installation.