Should my aftermarket frame have a serial number on it? I was riding a mostly custom WTP Crysis frame which had a serial in case the bike was lost or stolen. I snapped the drop out arms on Sunday and ended up buying a new FBM Hard Way frame. I checked all over and haven't seen the serial numbers. Part of me thinks there should definitely be one, but I'm not sure where to look. 

Does FBM allow me to register it online? I don't want to be at the point where the only evidence of it being my bike is "I have this pic of it in my apartment" and a bike shop receipt. But my bike shop receipt only says "BMX 20.75" frame" and doesn't say make, model or even color.
I would be surprised if any quality frame does not have a serial number. Many manufacturers warn against frames with no number, or numbers scratched off, so your concern is somewhat valid and you should follow up on it. Also reading http://fbmbmx.com/products/frames/fbm_warranty.php suggests the frame should have come with a warranty card. 

Photograph the frame with the receipt and send it to them, specifically expressing your concerns. They will confirm fairly quickly if its genuine.