Do I need GST registration?

GST registration becomes mandatory once your aggregate turnover crosses the threshold, broadly ₹40 lakh for goods and ₹20 lakh for services (₹20 lakh / ₹10 lakh in some special-category states). It's also required in certain cases regardless of turnover, e.g. inter-state supply of goods or selling via e-commerce operators.

Below the threshold?

You don't have to register or charge GST. You issue a bill of supply instead of a tax invoice (no GST shown). You can still get paid the same way.

Once registered

You charge GST, issue proper tax invoices with your GSTIN, and file returns. Lekhae helps you issue compliant invoices either way. This is general information, not tax advice, confirm specifics with your CA.