Based on the information provided, Muralidhar needs to compulsory register his business.

According to the Goods and Services Tax (GST) regulations in India, businesses with an annual turnover of more than ₹40 lacs (₹20 lacs for some states) are required to register for GST. Muralidhar’s turnover for the financial year 2022-23 has already reached ₹40 lacs, and it is mentioned that his turnover touched the ₹50 lacs mark on 10th December 2022. This means that he has exceeded the threshold for GST registration and is obligated to register his business.

Additionally, Muralidhar’s decision to expand his business to other cities in Karnataka and to supply paper cups to other states like Maharashtra, Kerala, and Tamil Nadu further strengthens the need for registration. Selling goods across state borders typically requires GST registration to comply with inter-state trade regulations.

While Muralidhar may have initially benefited from relaxed registration norms due to the nature of his business and the cash-based transactions, the expansion of his operations and the increase in turnover make it necessary for him to register his business to comply with tax regulations and avoid potential penalties or legal issues.