Profile datastore from purchase
Jamroom Developers
Sounds like you're wanting to make a module, nice one

Each module can have its own datastore, but only one datastore per module. (you can however have as many regular MySql tables as you need to support your module)
Developer docs are here:
Docs: Module Developers Guide
https://www.jamroom.net/the-jamroom-network/documentation/module-developer-guide
Creating a datastore for the module is as easy as adding a line to its schema.php file. Take a look at other modules with schema.php files for reference.
"When a user purchases a specific item a function needs to happen to show exclusive items because they made this purchase. "
Thats the "Events and Listeners" system, add a listener to your module to an appropriate event to check whether the event meets all your required criteria.