What are the measures to keep your private key safe and in memory ? Are there any alternatives to retrieve the key back ?
I dont think to should believe your memory, write it down somewhere. Better to have it on paper in printed way, because your PC can be hacked. Put it in safe place, do several copies.
That is true, the best way is to put it in some "material" way cause this is the safiest option that could be done in this internet era.