I had an augmentation with alloderm sling and implant. I am still uncomfortable . How long before that stops?

Usually it is not the Alloderm but the sutures that are placed to hold it until it incorporates. These are usually slowly dissolving over several weeks or longer so that the fixation doesn't come loose too early. A lot depends on what else was done - size and type of implants, previous surgery, etc.

Conceptually, the alloderm can function as an "internal bra" which supports both the lower and lateral extent of the implant, giving a fuller shape to the breast and enhancing the appearance of the cleavage area.  The material itself is very soft and is designed to be a scaffold along which your body can plant its own sells that will ultimately essentially replace the alloderm.  This process begins after the first week or so when your own blood supply grows in, and can take up to a year.  How uncomfortable this feels and how long it takes to go away varies by the individual but it's very unusual for the alloderm be felt after six months.