If the counter top is natural concrete it will stain.

If the concrete has been sealed with a special sealer it is less likely to stain. Remember, plain concrete is very porous.

Hot pans on the counter top will cause sealers to discolor.
Be sure and use trivets under hot pans.

Google and you will find loads of information on how to maintain the counters.

You have to seal it every 3-4 months, you have to wipe wine and any other staining spills (don't leave them overnight), NO HOT dishes on concrete. Chips if you aren't careful.

Also watch acids like lemon juice. I had chocolate brown concrete counters in my kitchen and green ones in MB. The bath counter is fine 11 years later, but the kitchen counter etched, peeled and looked like hell. It go replaced in 2010 thanks to a slab leak. I would not use concrete again in a working kitchen, but love it in the bath.

I have concrete countertops, made them myself, and what people are saying is probably not true about yours. They are almost certainly sealed, they look very professional and sealing would have been part of the creation of those custom countertops.

You certainly should not have to re-seal it every 3 months, if a good sealer was used. Some people use concrete wax to buff it up and protect the sealant, the wax does need renewing every 3 months, but that's usually for a higher-traffic kitchen counter.

The sealer itself should last much longer, and that will depend on how much you scrub the countertops of course. Every time you do you'll remove a bit of the sealer, some are harder than others. Since you didn't put them in you don't know what kind of sealer but I used acrylic on mine. Epoxy tends to look more plastic-like and can scratch and peel if not properly applied and bonded, yours does not appear to be epoxy.

You can easily test if the sealer needs renewing by putting some water on the surface, if it sinks in right away as if the concrete is "thirsty", it needs re-sealing. It would be good to know what type of sealer was used originally if you can find out. If you can't, it's probably safe to use one like Cheng concrete sealer - you can find it on Amazon.

For cleaning, I simply wipe it down with a damp microfiber cloth. I used a Mr Clean magic eraser once to get a scuff mark off. I don't use cleaning chemicals. Our countertops are about 2 years old now and have not stained, and I have not re-sealed them and I never waxed them.

In a bathroom, as long as you don't get hair dye or nail polish remover or something on it, I can't imagine there being a lot of wear and tear on it.

Tinan, please explain more of this concrete wax and how to apply it.