No, gains can be temporary and cemented. Temporary gains over time become cemented. For example- if you use
Bathmate and pump for 10 minutes, if you get an expansion of an inch- this is temporary expansion. If you keep this routine up for a few to several months- you will cement the gains and they will stay there forever. Cementing takes time and patience- this is why PE requires time and DEDICATION!! Now, no one can tell you whether your gains are fully cemented or not, but there is a safety 1/2 inch everyone is advised to gain after their final goal to just not lose anything of their final goal. It's purpose is JUST IN CASE if your gains are not cemented- for you not to lose any from you final goal. Example- your dream size is 8 inches, you gain till 8,5 inches, so when you stop and IF your gains are not cemented- you will drop down to 8 and no more. So that way you still have your final goal dream size. Get it?