Optimizely has gone through multiple price revisions in the past couple of years. Optimizely X (the latest avatar of the solution) prices its plans based on the formula:
Cost of the Optimizely License ( this includes the cost of Impressions) + Cost of Services Rendered.
The license automatically renews every year. The impressions start at 10 million as a base and can go up to 25 million a year, beyond which increments come in blocks of at least 25 million impressions.
It is unclear what the “cost of services” covers.