A pilot that ends with "thanks, it was interesting" is not a failure of the product as often as it is a failure of the plan. Conversion is decided in the first week, not the last.
Agree on success at the start
In the first call, ask the tester what would make the product worth paying for. Write it down and repeat it back. In the last week you are not selling; you are checking whether that result happened.
Talk to the person who pays
In a small business the tester and the buyer are often the same person. In larger teams they are not. Ask early who signs off on new tools and invite that person to the final review.
Fix one painful thing, visibly
Testers forgive missing features. They do not forgive being ignored. When feedback arrives, reply, fix the worst issue first and tell everyone it is fixed. A changelog update to testers every week builds trust quickly.
Name the price before the end
Price should never be a surprise in the last week. Put "pricing after the pilot" in the offer, mention it halfway through and make continuing a simple yes.
Track it honestly
Count accepted testers, active testers and paying customers. A pilot-to-paid rate of even 20 to 30 percent is strong early traction, and it is far more convincing when it is public.