Hi , if the Authorised supplier upgrades system memory capacity from stock item spec in shop as part of a negotiated sale I  would suggest ensure upgrade module description is included as a separate item on the sales receipt and including module model number.

In my opinion regarding post sales memory upgrade by the owner , that being not defined as a modification or repair , while laptop is under warranty,  is a Toshiba sanctioned owner upgrade as implied by the detailed procedural description in the user manual , , sect 4 - 29, however to ensure absolute peace of mind regarding continued warranty cover install only Toshiba  prescribed memory modules. 

shttp://www.mytoshiba.com.au/file/web/resource/pdf/warranty-statements/Toshiba-Notebook-AiO-Warranty-Stateme...

possibly these listed via link but check specific laptop model support page

http://www.mytoshiba.com.au/products/computers/satellite/l850/pskdla-0c900r/accessories

(scroll down somewhat)

re Windows 32bit / 64bit , if this model Toshiba laptop has 32bit Windows installed , executing a factory restore ( via the hidden partition stored on the hard disk drive) will option either 32bit or 64bit Windows , owner selectable

ps : don't forget to run a full oem Windows recovery disk set in case the hard disk drive fails or a future Windows operating system upgrade deletes the hidden recovery partition and you seek to restore to the native os version

Hope this helps