There are a lot of blue-purple clematis. How accurate does the color of the photo seem on your computer? (blues are notoriously hard to photograph, and yes I know that my computer screen may vary)
When does it bloom and for how long?

One thing you can do is type in the particulars (height, bloom time, bloom color, etc,) leaving the parts blank that you don't know, on the search form of Clematis on the Web to see if you can narrow it down. Once you get a list, click on the names and you will see photos. Look at both the leaves and the flowers to see what is a close match.

You can also ask the grower to next season peg down a branch at a leaf node and see if you can get a new plant. Then the name wouldn't matter.

Here is a link that might be useful: Clematis on the Web search

Could be The President

Wow! Could very well be the President! I looked it up and it does resemble very well. Thanks Gary.https://www.google.com/search?sourceid=chrome-psyapi2&rlz=1C1GGGE_enUS561US570&ion=1&espv=&ie=UTF-8&q=the%20president%20clematis

I haven't seen The Pres. that blue but Rhapsody can be.
Is that fanTAStic or what???!!! Next time, also take a closeup so people can see the petal shape and number, and the leaves.
mindy