You have to ask them to clear coat them over the decal. then they last 25 years. They may want YOU to place the decals exactly where you want them.
If you have a nice metal tank, it will never fall off or come loose once clear coated; Getting them in the correct position is the tough part.
Plastic tanks let fumes out and have to be Kreemed or Red Coated prior to any decals being applied.......
In the end you will have a super nice tank, worth some bucks so NO CRASHING your knees into it
All our government does is distract us while they steal from us, misspend our tax $ and ruin our country