ASK USERS TO REGISTER AT THE START (NOT THE END)

Summary from the TLDR Marketing newsletter

Asking users to register at the start of shopping increases registrations, purchases, and long-term revenue. In a field experiment of over 75,000 users, early registration made shoppers 58.1% more likely to register and 10.9% more likely to buy. Those shoppers bought 16.8% more items and generated 13.2% higher total revenue over a year. Casual shoppers browsed 12.3% less after early registration prompts. Optional registration prevented short-term sales losses.