No it isn't... In Canada, you can happily accept money from people and just stick it in the "other income" box on your tax return, where it'll get income-taxed appropriately.

If you're trying to do business deductions or want to pay business taxes instead, yes you need a business. If you're trying to set up a physical location, yes you need a business license from your city. But if you don't care about the pennies and your work is digital there's absolutely no requirement.