Many places now will only do 80 & 150cu^ft private tank sales / leases. Unless you're willing to get on their file & have a credit check done. Which is gay...
At any rate, if you take proof of ownership papers into a gas supply/distrobution house. They'll fill it being their's, or someone else's. The reason places sometimes tell you only if it gcame from here. Is they're wanting proper testing dates & they want some owner on file.
Personally I have an 80 & a 120, and I hate both the *******. Small tanks are TOO MOTHER ------- EXPENCIVE to fill to be worth having them. I plan on stepping up to a 320-380 sometime this fall. I'll probably keep the 120 & sell the 80 back to them for it's market value in cash or store credit.

And gas prices across the nation have been horrible this year... Oh my god 100% argon in an 80 was $30 to fill in Feb, $35 in march & they're at $40 in late april. A 320 tank is still at $75. That's a 105% gas mark-up between the two tanks.