You can get the updates for free if you have bought the pack once. Everytime you want to download it you will be given the newest version of the pack
Viewing post in Modern interiors - RPG Tileset [16X16] comments
All the interior items are split in themes. For example, the reception scene is made from items in 1_Generic and 5_Classroom png files.
Talking about the licence it is all writen in the description:
Complete version LICENSE (paying at least 1.20$):
YOU CAN:
- Edit and use the asset in any commercial or non commercial project
-Use the asset in any commercial or non commercial project
YOU CAN'T:
- Resell or distribute the asset to others
- Edit and resell the asset to others
Credits required (this link)