Generally, you can check whether or not your supplements are banned by looking up the information online and checking that supplement against various different organisations’ ban lists. Those lists of banned products by, say, the FDA or the WADA would be able to let you know what’s banned and not what you’re allowed to use and not.
You can use this information to make a decision on whether or not you want to buy supplements. If you’re looking to enter some kind of competition or compete in some kind of event, you’ll probably want to be sure you’re allowed to use the kinds of supplements you plan on employing.