How do you earn back a partners trust?

i’ve been dating my bf now for a year and a half. about 2 months ago we broke up for a month. now we’re back together but we’re not exclusive anymore... we’re open. mainly bc he doesn’t trust me anymore i guess. i never cheated on him, i was never mean to him, he doesn’t trust me bc i used to go on his phone and go behind his back w being too nosy. i only did that bc i found out he was going to massage places an alarming amount of time... and he wouldn’t tell me so i wanted to know more about it. we got back together bc we still love each other and what not. and he says it’s gonna be awhile and take a lot for me to earn back his trust. so i need to prove to him that he can trust me. is there any tips where i can prove it to him? anything would help.

ps- he told me to: not go on his phone, stop looking over his shoulder, and to maybe clean his apartment and prove i care. he tells me i’m the most loyal girl he’s ever met and that he cares he just can’t be in a serious relationship if he can’t trust me.

pss- another reason i’m worried about him and felt the need to track him is because of this: he’s a 27 year old ex heroine addict that still lives off his parents money and his mom pays for his apartment by the beach. he gets $4,000 a month or something from her and he has never had a serious job. he’s still in school, doesn’t have any hobbies except smoking weed and occasioanlly goes out with his lowlife friends who do nothing but go to bars together. he literally just got an internship of not having a job for like 4 years... and he used to verbally & emotionally abuse me. he buys weird china drugs online and doesn’t tell me JACK SHIT. so ya. you tell me who rly can’t trust who. and there’s probs more but i’m forgetting rn