If you notice a usage limit on your account, it means your provider has decided to set a cap on how many interactions (or how many documents) you are able to use in a given period. This ensures all students have an equal chance of using the service.
You'll see your allocation on the right hand side when logged in to your Studiosity account homepage:
If you would like more support, we suggest speaking to the student services and/or student union at your institution, to let them know. It's important for them to receive this feedback from students, and they may be able to point you in the direction of another service available to you.