Session replay is an add-on feature for paying customers only. You may try the feature for free for 14 days or 10,000 sessions (whichever comes first), after which you must contact Sales to continue use.
Session replay is for Web only. Native mobile (Android, iOS) session replay is not currently supported but is on our roadmap.
Heatmaps are generated from sessions that were captured when your environment had session replay capture turned on, and can look backward as far as 30 days.
For example, if you turned on session replay capture on June 1, then that would be the earliest day you could include in heatmaps analysis, up until July 1.
For best results, we recommend you select date ranges between 7 and 30 days.