I was thinking that you can maybe add a badge or something on the dashboard that can show your money that you saved from buying a library for example I bought a bronze Library for $100 and it is valued at $600 then have a badge or a tile on the dashboard that will show $500 saving. You can also expand on this or make a different one for the people that get 5% savings and cashback you can have a seperate badge or dashboard tile that says the all the 5% discount in total you got to date. You can include the cashback into that number but it would be better separated. This can be a powerful tool to show people the amount they save using your platform. So they see how thier money is working for them and also the value they are getting from using your platform.
So In theory it can look something like this:(just Random numbers to display the concept)
Total savings(excluding 5% discount) $9,580(to date)
5% subscription savings(to date) $839
5% cashback(to date) $658
Thank you and God bless