storing information in a users account

Currently I sell 2 products to my customers. These 2 products come with schedules that my customers follow on my website. Currently i use 2 generic accounts to accomplish this. i now want to move away from the 2 accounts and begin giving each customer their own accounts that they can log into and utilize the schedules and other logged in features. I dont want them to be “WordPress” users aka No dashboard access but I do want to be able to store information in their own user account as I develop new features for logged in users. I am currently using the Membership plugin and i use Gravity forms to create the user accounts.

I am looking for some guidance and direction on ways of accomplishing this. I am looking at giving my customers an account that they can use for better customer service and I can use to store information and sell them products that they can better use.

Thank you