How to make 1 Day and 7 Day Mounts Permanent
First off please understand that this is technically just a glitch in the scripting of the mounts. They rely on timers which are syncronized with your computer's clock rather than with the game's internal clock.
So how do you make the mounts permanent? It's easy! Just buy which ever mount you want. It doesn't matter if they are 1 day mounts or 7 day mounts. Just buy one you like. If you get a 1 day mount simply exit to the character selection screne then right click on your computer's clock (should be down in the right hand corner of your desktop). Select Adjust Time/Date and roll the days ahead by 2. If you choose a 7 day mount instead then simply do the same thing but roll the days ahead 9. select the same character you were using and then click to begin playing. Check your mount in your inventory and you'll notice that the timer on it now reads all 0's. You can continue to use this mount now forever and when the 2 or 9 days have passed you can even change your clock back to normal and your mount remains perpetual. ;)