This is true if you do what most people do and donate the minimum £10 to get the perks however if you donate more money you can get the forum tag for longer. The days of donator for each amount can be found on this page https://www.roleplay.co.uk/donations
You get to keep the little coin stack though, if youre like me and donate £10 then you get it for one month, and if you donate certain figures like I'm gonna be doing you get cute little things on the forum like a weed plant for 4.20 XD