Some gifts are received by Sales Campaigns! Sales Campaigns promote you to purchase products. For example, if you were to buy premium for x amount of days they will throw in a mount or outfit. The best way to know if a Sales Campaign is available is to continuously check Tibia.com for the latest news. However, I haven't seen a Sales Campaign in a while. If you want to see if you ever participated in a Sales Campaign a good way would be to check Tibia.com as the store in-game won't show you the details regarding Sales Campaigns History. Please note this section on Tibia.com is only available to those who actually participated in a Sales Campaign, if you didn't this option won't show under History)
Here's an example of what is displayed on in the store in-game, however it doesn't give you the option in store history to see the details or view how you even received this. Interesting because these mounts were received way before 1/23/2020.
However, the Recruiter outfit is also displayed as such!
To view more information you can Go to Tibia.com, Login, Manage Account, Scroll down to find Sales Campaigns Assignments History and click on View History (shown in the red box below) Please note if you didn't participate in any Sales Campaigns your account page will not have this section available. However, if you did receive the Recruiter Outfit and you wanted to know how click the Tell-A-Friend button and it will tell you how you received it as this is different than a Sales Campaign.
In this section, you see all special offers which you have ever received in sales campaigns. If you have received a reward that you have not assigned, yet, you can click on "View" to assign your reward to one of your characters. When you click view it doesn't give you much more information as to what the Campaign was about.
You'll have to do some research as to the particular gifts if you aren't sure how you got it. For me, what I do is I'll research the mount on fansites, like Tibia Fandom. It will display information without you having to go through all the Archives on Tibia.com
While this mount was added to the game with the Update 9.1, it was only obtainable during a special offer by buying a unit of 180 or 360 days of premium time between August 29 and September 12, 2012. Buying the premium time only let you assign this mount to one character. It is possible to follow the offical FAQ made by CM Mirade here.This mount has been available in the Store since September 15, 2017.
https://tibia.fandom.com/wiki/Armoured_War_Horse