Please point me in the direction i need to go.

Basically i need an in app "currency" that people can earn credits by viewing ads specific to one region(i can get individual adds and put them in myself) and say for example viewing the businesses ad you get 5 credits or points. With those points you can then go to businesses that accept the credits or virtual currency, as part payment for an offer etc, something small but useful, ex. A small local phone repair shop that accepts 100 credits for 30% off a phone case etc. (Bad example but forst thing that popped up). The thing is i need a way for the currency to be secure and when tou want to use an offer, you press on it and a qr vode pops up which the shop scans and deducts the points from you, meaning the vanish(not go to the business as ifs not a currency, but a coupon sort of thing), but every qr code should be user specific unique and single-use, to deduct the points from their account, and so other people couldnt screenshot your code and rob your credits. I explained it in a very complicated way but would appreciate any help. Thanks, ps i know these things exist.

Just looking for someone to point me in the right direction

So I decided to root my phone ...I used the latest Windroid toolkit ..now I was able to unlock the boot loader and install/flash TWRP. here is my issue when I click on the Flash SuperSU button I get this error "wrong device state ! please ensure that your device is in Android! any help on how to finish flashing it would be appreciated.

Windroid toolkit 3.1.0

Thanks:o

Newb needs some direction

Hiya I got a tmobile l90 d415 Its software is on d41520c 5.0.2 an so far its rooted but i think i need to unlock the bootloader an maybe install a custom rom. Im just not sure about which process to unlock my bootloader. Thank you everyone on xda for supporting this cool phone! :)