You're right, the term is freeware (but with the right to donate
But
I do get prompted to donate every now and then when I launch Transmission.
This is the page where I made a donation (with VISA):
http://www.transmissionbt.com/donate.php
I think it's perfectly fair to donate (that's why I did it), only I don't think I should be prompted to donate again and again when I already did.
I think it's Transmission I'm running

(Plese let me know if there is a better way of checking this)
Under menu
Transmission > About Transmission
I find the following:
Transmission 2.77 (14031)
and the following:
------------
The Transmission Project
http://www.transmissionbt.com/
Lead Developers <
dev@transmissionbt.com>
Jordan Lee <
jordan@transmissionbt.com> (Daemon, Backend, GTK+ client)
Mitchell Livingston, Digital Ignition LLC <
livings124@transmissionbt.com> (Mac OS X client)
Kevin Glowacz <
kjg@transmissionbt.com> (Web client)
Project Contributors
John Clay <
john@transmissionbt.com> (Website maintenance and troubleshooting, Mac OS X help documentation)
Bruno Bierbaumer (Web client patches)
Juliusz Chroboczek (DHT, network code, BitTorrent code improvements)
Daniel Lee (Patches)
Tomas Carnecky (Profiling, patches, and detection of sneaky bugs)
Diego Jiménez (Patches)
Kendall Hopkins <
SoftwareElves@gmail.com> (Web client)
Malcolm Jarvis <
mjarvis@transmissionbt.com> (Web client)
Rashid Eissing (Mac OS X Transfers preferences icon)
Hugo van Heuven, madebysofa (Main icon design)
Andreas Nilsson (GNOME adaptation of main icon)
Dean Ostetto (Mac OS X Turtle image)
Rick Patrick (Mac OS X images)
Jonas Rask (Mac OS X Globe icon)
Erick Turnquist (IPv6 code, support)
Maarten Van Coile (Wiki Wrangler, troubleshooting, support)
James "Kibo" Parry (Updated Mac Retina images)
Previous Developers
Eric Petit <
eric@lapsus.org> (Project originator)
Josh Elsasser <
josh@elsasser.org> (Daemon, Backend, GTK+ client)
Bryan Varner <
bryan@varnernet.com> (BeOS client)
Mac OS X Translators
Jorge Carrasco (Spanish)
Etienne Samson (French)
Marco Cavazzuti (Italian)
Anton Sotkov (Russian)
Alexander Bykov (Russian)
Maarten Van Coile (Dutch)
Guilherme Fernandes (Brazilian Portuguese)
Sven-S. Porst (German)
Tianhao He (Simplified Chinese)
Sérgio Miranda (European Portuguese)
Daniel Østergaard Nielsen (Danish)
Third-Party Resources
Niels Provos for use of libevent. <
http://monkey.org/~provos/libevent/>
Thomas Bernard for use of MiniUPnP and libnatpmp. <
http://miniupnp.tuxfamily.org/>
The Growl Development Team for use of Growl. <
http://growl.info/>
Andy Matuschak for use of Sparkle. <
http://sparkle.andymatuschak.org/>
M. Uli Kusterer for use of UKKQueue.
------------
Greetings
Anna