You add the extra permits like trout stamps for the life of the license- you get 3 or 5 trout stamps. You can also get the trout-Lake Erie combo this way. You can also add stamps on later if you don't get them when you get the 3 or 5 year license.

It's not a bad deal. You save a few bucks and get a free Angler magazine subscription and some discount coupons. Most importantly for me, I won't have to rush out in the middle of ice fishing season and get a new license.

The PA Fish and Boat web site has more info on their FACs page.

Like allegnmnt said. It's just the same as it was for a single year only with the option of multiple years and also like he said any license/stamp you don't get you can always add whenever you want.
I don't know if you can buy for instance a 5 year license and 2 years later buy 3 years of say an erie stamp. I think any license not purchased initially will be sold by the year.