[Grammar] The present perfect

[Kazuo]

Hello!

A caution (on a library book)
This book must be returned on or before the date last marked below unless permission to renew has been obtained.

In the sentence above, is the use of the present perfect mandatory?
Instead, is it acceptable to say unless permission to renew is obtained, or unless permission to renew is yet complete?

Thanks in advance

 

[bertietheblue]

Hello!

A caution (on a library book)
This book must be returned on or before the date last marked below unless permission to renew has been obtained.

In the sentence above, is the use of the present perfect mandatory?
Instead, is it acceptable to say unless permission to renew is obtained - yes, though I'd prefer 'is first obtained', or unless permission to renew is yet complete - no, you don't 'complete a permission'?

Thanks in advance

Bertie