My Mom was diagnosed with Alzheimers 3 years ago or so. Her short term memory has been non existent for almost a year now, but her long term has always been pretty good. All of a sudden people that she knew from years ago that she has remembered she doesn't. For example she has always talked about some people that we know in Denver, haven't seen them in years but she gets a Christmas Card from them every year. She got one this year but could not place who they are. I know Mom will eventually forget who I am too, when it happens will it happen that quick?
Of course, with her, even early on, she could not recall the name of her high school or college, even though she remembered people she knew from that time frame by name.
I just try to keep an open mind. I know that eventually, she will not know who I am, though, I believe she will always like me and be glad to see me as long as she is aware of her surroundings. I think this because the staff tells me that she talks about me and says good things about me. And when I visit, she tells me that she loves me and that I mean the world to her.
She may one day forget your name but remember that you're her daughter. Or she may forget your name and who you are but like PCVS above me said, hopefully there will be emotion she can tie to you like love, security, and safety and that you are someone important to her.
Long answer: she may forget suddenly and never recall again, or it may come and go. And then go and never come back. But if you are loving and cheerful, she will have the emotional memory of you long after she can't recall your name.