Adding this up here for visibility
Continuing the discussion from 100 Boost for 15th Anniversary:
Just found out how to unlock a free level 100 boost from WoW’s 15th Anniversary promotion from a friend.
The boost is not offered to currently subbed players. However, all you need to do to get it is cancel your sub (even though still having game time) and wait a while. Eventually the promotion will be offered, simply claim and resub.
Worked for me. Please share and Good luck!
Thanks for the heads up. Unsubbing now.
What!? What the heck is that nonsense?
I still havent used any of my boosts :l
I have game time, but currently do not have an active sub. I did not get a 100 boost. 
Hey I want a free level 100 too.
They’ll either fix the loophole, fix it and action accounts that used the boost, or give one boost to everyone.
I wonder what way they will jump with this. Either way I won’t do it until the dust settles on it.
I boost my bank toon each xpac.
I feel like this 100 boost is a troll.
Easy peasy. Even got dmf mace to drop for the toon
K
I have 3 accounts, 2 are inactive. 0 boosts. 
Alright, wait… I haven’t paid for a subscription in like 5 years, its all WoW token 
Ya I hate leveling shamans but my ocd forces me to have one of each class at max. I think I’ll hold off on leveling this toon. Just in case they revert it.
Would be funny.
People who quit? Free boost.
People who are loyal? Revert free boost.
Yup but you know how weird they can be. The whole thing rings alarm bells to me.
I don’t have an active sub but buy my time as I feel like it. Haven’t received a boost offer, and if I did I’d probably send in a ticket and confirm it’s not going to be caught up in some kind of scandal like that xp one recently.
Desperate measure for desperate times. Really a free 100 boost. Blizzard are desperate if you ask me.
Well I’m not knowingly exploiting. They can revert it, all I did was claim a boost
Yup but as I mentioned about the xp pot fiasco, for them the “I didn’t know” reason didn’t cut it. Doesn’t mean those people did or didn’t know, but they came down super hard.
I’d maybe pop in a ticket and make sure you’re in the clear. If it’s all intended then sweet. If it’s not at least you were honest and queried it.
Blizzard is a funny beast. I’d just play things safe.
Uh, y’all doing this should be careful. This is a clear exploit. They may or may not care, but…tread carefully and don’t brag.
My current month is via token so there’s no sub to cancel, and I didn’t get a boost.
I checked my mail still no 100 boost, wth Blizzard? Pls.