How can I convince my Mum to let me stay at my boyfriends?

I live in Plymouth he lives in Liskeard. My Mama doesn't know he lives on his own I told her that he still lives with his mum. I'm 17 and he's 18. She refuses to let me stay the night. What can I say to convince her to let my spend the night there. She treats me like an adult in every aspect of my life until it comes to going out. I have to be in at 11pm and If I'm spending the night somewhere she has to know, who, where, how am i getting there, the home phone number, address. She has reasons not to trust me I've lied once or twice before but I'm a teenager i'm gonna make mistakes and she doesn't seem to understand that. The thing is a lot of the time i have to lie or I wouldn't be allowed out. I get in trouble for being honest so lying seems the best way. She's even tried to ban me from seeing certain friends. It's Friggin ridiculous. HELP. I just want to fall asleep cuddled up to my BF :(