Your trial version should automatically become the professional version as soon as you plug in the license key.
Has the key been re-programmed (upgraded) so that it is suitable for 15?
If not you will still only have the trial (demo) version.
Follow this link to check / upgrade your key.
http://www.archicadwiki.com/RemoteKeyUpgrade
Barry.
One of the forum moderators.
Versions 6.5 to 27
Dell XPS- i7-6700 @ 3.4Ghz, 16GB ram, GeForce GTX 960 (2GB), Windows 10
Lenovo Thinkpad - i7-1270P 2.20 GHz, 32GB RAM, Nvidia T550, Windows 11