Don't sell me, tell me
Just tell me that the free "plan" only allows 1 document compression per day.
At least that's the inference I'm making from your vague, protect-yourself message.
Putting the work on your users rather than sneakily pushing to a subscription is more annoying than it needs to be. As I said, just tell me the costs of "free". Now I'm off to find a competitive product or service that treats its customers as adults.