Unfortunately, yes. You will need to collect and pay GST after you register in the system. If you never make over $30,000, you don’t need to register to collect GST in the first place. So, avoid doing that if you can. However, if you do it once, you'll need to keep paying it until your situation changes.
If you registered because you passed the $30,000 threshold before, but you don’t think that this will happen again, you could try to change your situation now so that you won’t have to pay it next year.