There are two scenarios that I see.
You have a mortgage on the property. Generally the insurance company sends the funds to the lender, who then releases the funds to you as you make the repairs. They do it this way because if you never make the repairs the value of the collateral is decreased, and the lender wants to protect their investment.
There is no mortgage. You will get the funds directly, and the insurance company will not force you to make the repairs especially if the repairs are cosmetic in nature.
In either case if you don't fix the cause of the leak, and make repairs to the site around the leak, you will run into a problem in the future if the leak continues, or the rot and mold continues to spread.
If you file a future claim they are likely to ask for proof of the original repair. If you didn't make it, they are likely to deny the second claim. They will say the cause is the original incident and if you had made the repair, the second incident wouldn't have happened. They are likely to drop you at that point.
If you try to sell the house you will have to disclose the original leak, and the potential buyers will want you to make the repairs. Any mold or rot spotted by the home inspector will be a big issue for them. It is also likely to be an item that they will be advised to demand that you get a legitimate company to make the repair before the deal can move forward, and won't negotiate a lower price or a credit for $x so they can get the repair done. Some will just cancel the deal based on the inspection report.