Just got registered and have a question

I just got out of DMV where I spent an hour with the wicked DMV witch who tried to tell me I built my trailer from a kit and wanted the receipt for the kit. I finally convinced that evil woman I built it myself and it only cost $300 in parts ( I dont feel guilty at all for lying to her! ) anyway I ended up with a "California Perm Trailer" Licence plate,total cost was $47, What the heck does that mean? I dont see an expiration date on the paperwork,do I never have to register it again?
I just wanted out of there so I didn't bother asking the DMV devil about it, I just ran! Thanks if anyone knows! Aaron
I just wanted out of there so I didn't bother asking the DMV devil about it, I just ran! Thanks if anyone knows! Aaron