I'm not aware of a total limit for free accounts. You need to accept the nsec.app connection request. If you're on iOS, there's special instructions https://nsec.app/ios.html. It's much easier to use a nip-07 extension though. I use  @nostore on iOS. 

 No limits for free usage, just the file size. 

 et pour Android  

 https://nsec.app should work, but I haven’t tested 

 thanks you .i am sée this