You have access to the list of users you’ve blocked or declined. All you have to do is go into the “Users Declined / Blocked” tab in “My Preferences”. You can change that list at any time by unblocking or accepting a profile you’ve blocked or declined.
Would be nice if this option was actually visible. If this is a premium-only function, at least include this in the explanation :/ i accidentally tapped away a like i was really interested in, and now it really seems like i’m never going to see this profile again, without any actually available way to get the profile back.