Sure, you can use it without limits, but it will cost you:
$10 per GB past your plans monthly contracted amount.
So they don't stop you from using it (so it's technically 'unlimited'), but you will just get a bigger bill if you exceed your contracted amount.
Good luck, better check your monthly bill to see if your unlimited contracts ends soon.
I used to have a Verizon Unlimited plan on my cell phone. They did everything they could to try to entice me to get off that plan after they ended it, and I was grandfathered in, so I kept it. But then they forced an end to it, and I had to purchase another plan. If another network had the coverage that Verizon does, I would have jumped ship.
Wouldn't you know it, about 8 or 9 months after they forced me into another plan, they then came out with a 'new' unlimited plan. Unfortunately the cost was not inexpensive for one user (I think the price is almost reasonable if you have four family members on it).
At this point, I'm not traveling as much as I used to, so it's not as important for me to have unlimited data on my cell phone. I also installed a nice WiFi hot spot on our dock, so when at the boat, I have as much bandwidth as I need there.