The money-back guarantee lets a new customer try LumaDock with their first order: 30 days for a VPS and 7 days for a GPU VPS. It's meant for one honest trial, not as a free plan that renews.
Once the guarantee has been used, new servers on the account are not covered again. The conditions are in How to request a refund.
What counts as misuse
Ordering more servers and asking for refunds after using them
Ordering, using and canceling servers again and again to get refunds
Asking for another guarantee after a refund was already issued on the account
Opening another account to get a new-customer refund again
Using the guarantee as a free trial or as free computing power
What happens
An account that misuses the guarantee loses it, and later refund requests can be declined even inside the usual window. In serious cases, the account can be suspended or closed.
The full terms are in the Terms of Service.