Sorry if it was already covered somewhere but I don't really understand this. Here is the story. I had 3 boosters and was planning to use one of them the next day since I was already going to bed. But while just going around watering I got another booster from a red box. Next day, I clicked on the boosters (had 4 in total) but my only options were to either delete one or pay 2 diamonds. There was no option to activate one of the 3 boosters I had before the 4th.
At first I thought that maybe even active boosters occupy one of 3 slots but that's not the case. After deleting one of 4 boosters and activating one of remaining 3 ones I had 1 free slot.
Am I missing something? If that how it works then it seems a bit unfair. Essentially I forfeited a booster for nothing. Feel a bit cheated here... I don't always have a use for the boosters because they're timed and can't know when I might get one. They are also rare. And it's not how it works with other items. E.g. Gift cards - we can use up the existing ones before adding more. We don't have to just lose them.
To be clear - I'm not suggesting unlimited accumulation of boosters, but IMHO we should be allowed to activate a booster to free up a slot and then deal with remaining boosters.

