how do i know we’re going to last

so me and my boyfriend have been together for 11months and honestly we’ve been through a lot but lately i’ve been so worried that our love might fade and we might not make it i know i’m only 17 and it’s kinda crazy but i want this so bad for myself how can i make sure that we stay fresh happy and last a super long time?? also i’ve been catching him in a few lies about smoking and sometimes i’m really tough on him when he goes out with friends because i think he’s smoking and lying again and i don’t trust him around his friends (who aren’t good people i should mention) and he wants me to start trusting him again how do i do that???? someone helllp