My Prism Art Studio from The Sims 3 store isn't showing up for me s I can put it in my town

Try this from the Store FAQ

 I can't find the venue I've installed

Venues are especially tricky and if you have a lot of content, have the tendency to not install at all.

First make sure that it's really not in your game. You should find the venue in the edit town in the community lot library. Sometimes they don't have a real name but only numbers. The icon they have also varies from showing as Store Content (the little shopping bag) to user-created content (red rosette).

If it's really not in the game, install it again, using this method:

• Close the game and launcher
• Backup the whole folder documents\electronicarts\thesims3 to an external drive or some other safe location
• Move the folder DCCache to the desktop
• Start the launcher. ALL of your custom content except houses and Sims will be gone from your installed content. Not to worry about that.
• Install the venue again
• Check documents\electronicarts\thesims3\library if you have a new file which starts with ebf_ and has the timestamp fo the time you've installed the venue. Start over, if you don't
• Delete the newly created DCCache folder in documents\electronicarts\thesims3 (NOT the one on your desktop)
• Move the DCCache folder from the desktop back into documents\electronicarts\thesims3
• Start the game. The venue should now be in your library and you should have all your stuff back as well.
• If anything goes wrong, replace the whole folder with the backup you made.