Exporting specific data

I was just wondering if it would be possible to export specific data made by a user or group of users at once and then import it into a different app?

For example, the user could use a free version of my site and they could have 2-3 other users on their team. If they buy a plan they would be moved to a sub app so their version could be fully customised among other things.

If I have hundreds of other users using the site too, could I cherry pick their data and export it then import it into the sub application?

Also would these users need to create new accounts or could I transfer them across too?