If you can see this message, it could be due to the following reasons;
First and foremost reason for many accounts getting suspended is for not paying hosting bill regularly or by forgetting to do so.
Plagairsm is nothing but copyright violation. Publishing other`s work/article as your own or by posting other`s copyrighted content without their permission can lead to serious trouble.
This is one of the most dangerous reasons to get your account suspended. Intensive spamming on other`s website to promote your website will lead to suspended account. Though spamming is not so dangerous, Phishing is deadly. If you use your website to cheat people by pretending or selling things online and illegally collecting their Credit Card / Bank Account information to make money, your hosting account gets suspended and you may face lawsuits by the cheated customers.
Using your website to host illegal content such as pirated software, movies, music etc will lead to suspended account. Even hosting torrents will lead to the same. This is very dangerous and companies may as well file a case on you