In this modern age, it's understandable that people are concerned about being hacked or having their account stole. If it's happened to you before, then you'll know how frustrating it can be. The last thing you want is your LoL account disappearing after you've put in years of hard work.
As long as you buy your ELO boosting from a respectable and trusted booster, then there is no chance your account will get stolen or banned. Reputable companies use a number of different methods to make sure your account details are stored safely. In fact, the booster never actually gets to see your details!
In addition to this, good boosters will use various unique IP addresses are used so that there aren't hundreds of accounts linked to 1 IP address. By using these security measures, there is an extremely low chance your account will be banned or stolen. This means you can feel safe handing your account details over to someone, knowing that you won't be waving bye bye forever.