You can not write , this encrypted !

I need help , I bought the standard license for my project but need to select or highlight , and I jump an error:

You can not write , esta encrypted !
How can I solve that?

Are you trying to open-modify-write an encrypted file?
Are you passing the owner password to the library while opening the file?

I had the demo version , my plan worked perfectly, I 'm trying to select and highlight but do not let me

How the password is removed ?

Password can be removed resaving the PDF as unencrypted.
Resaving as new file is supported by Premium license.
Professional license can save modified PDF file over the original file maintaining the same encryption scheme of the original file.

You could change my standard professional license ?

Are you adopting a standard license?
Standard license isn't allowing you annotations.
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