Siri records your queries too, but she doesn’t catalog them or provide access to the running list of requests. You can’t listen to your history of Siri interactions in Apple’s app universe.
While Apple logs and stores Siri queries, they’re tied to a random string of numbers for each user instead of an Apple ID or email address. Apple deletes the association between those queries and those numerical codes after six months. Your Amazon and Google histories, on the other hand, stay there until you decide to delete them.
http://themillenniumreport.com/2017/03/not-only-are-alexa-si...
From Wired, “Apple finally reveals how long Siri keeps your data”, in 2013, about later disassociation from the tokens:
Once the voice recording is six months old, Apple "disassociates" your user number from the clip, deleting the number from the voice file. But it keeps these disassociated files for up to 18 more months for testing and product improvement purposes.
"Apple may keep anonymized Siri data for up to two years," Muller says "If a user turns Siri off, both identifiers are deleted immediately along with any associated data."
There is no need to send all of this to them. If I want to suggest a command, allow me using a simple form.
Interesting, I thought I had heard it widely reported that Apple was keeping hold of audio records tagged with your Apple ID for 6 months, before anonymizing. That looks like it wasn't the case, and Apple was only tagging those recordings with a device ID, presumably to associate recordings with other recordings.