Using a console like EarthCache, archive satellite imagery is a purchasing option for imagery that has already been collected. Archive imagery can be passively collected by satellites that constantly collect over the earth. It can also be collected based on users of the satellite tasking it to collect over a certain area. Those who task images through providers agree upon the terms and licensing to share this data, meaning that an individual outside of the organization that tasked the data can purchase what was captured via archive. Purchasing archival data is an affordable way to get data on a region you want to analyze.
For example, if you are a fan of the FIFA World Cup and are wanting to look at the stadiums, you can search for imagery that was tasked in the region and timeframe of the tournament. If another person has tasked imagery in that region, you will see it on the EarthCache console and can purchase the KM2 you are looking for.