Unlike most keyword tools that charge monthly, Keyword Chef only charges you when you find keywords. This works by purchasing credits, where each keyword returned in your report will cost 1 credit. Think of it as a prepaid cellphone plan, where you buy minutes and use them when you want.
Each credit includes:
Avg, high, and low search volume
The real-time SERP preview and SERP score
Looking up the SERP does not cost additional credits.
However, for users on the free trial, there is a limit of 30 SERP lookups. Paid users get unlimited SERP lookups.
Credits never expire and reports are saved forever.