Just an idea...

another one idea...

French term (edited): permis d'exploitation

The 'en' is a bit misleading - the emphasis should actually be on 'TRANSFORMATION en permis d'exploitation'. In other words, it starts out as a concession, and is later converted into a 'permis d'exploitation'.

Literally, this is an 'operating permit/licence', but I have found it translated as 'business licence'. E.g. here: http://www.ville.hawkesbury.on.ca/businapp.pdf.
I think either would work.

You're talking about an "exploitation permit" here. That's clear.
Used often in mining world.

"exploitation permit" is also called an "exploitation concession"

Now, now you have the word "concession" used twice, which is perfectly acceptable.

Example:
one can convert an exploration concession into a exploitation concession.

In this case, we are dealing with a concession (piece of land) which will be able to be legally exploited after the exploitation concession/permit is received.

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Note added at 8 hrs (2006-03-01 06:36:56 GMT)
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I've never seen: converting the concession to an exploitation permit".

the word "concession" is generally used twice.

You can also say "into" instead of "to". Example: into an exploitation concession

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Note added at 9 hrs (2006-03-01 06:52:40 GMT)
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I'd like to add that that word "conversion" or "to convert" is very important here. Try a google search, and you will see how frequently "conversion/converting of a concession into/to an exploitation concession" is used in English in this context.