Refunded? You can’t be serious.
Regardless of it being “Lifetime” let’s really look at what you’ve received:
If what you said is true, you purchased a control panel license and used it for 10 years after paying only $89.
That’s about $0.74 cents per month for 10 years.
Even if they took your money and closed their business after 1 year, that’s still only $7/month spent for a control panel license, which is far below market averages even in 2014.
Hopefully you can come to some agreement with DirectAdmin, but I feel like you’re being a bit unreasonable in your expectations.